FINAL REPORT
HOLOGRAPHIC DETERMINATION
OF INJECTED LIMESTONE DISTRIBUTION
IN UNIT 10 OF THE SHAWNEE POWER PLANT
JUNE 1970
prepared by
B. J. MATTHEWS and R. F. KEMP
UNDER NAPCA CONTRACT CPA 70-4
TRW REPORT NO. 14103-6001-RO-OO
TRW
SYSTEMS GROUP
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G'FF-IGAL t53:E 8NL:Y-
F .a1, interim and monthly reports sub:rp.itted under this contI'
contain i formation and statements which are pre1i:rninary and re. se.»t
only the s te of the information developed as of the reportfng te. This
information's also subject to review and critique by NAPCA ersonnel
before releas outside of NAPCA. To prevent inappropria. dessemi~tiO'n'
of information hich could be misinterpretedandl or mi . ,eading, you al"e
asked to regard ese reports strictly as internal wor ng documents and
treat them accordi ly. You are requested to obse e the {Qllbwing
guidelines:
(1)
ts for informatioJJ. nd co.ordination purpose$:
(2)
(3)
Refer all inquiries
Officer.
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FINAL REPORT
HOLOGRAPHIC DETERMINATION
OF INJECTED LIMESTONE DISTRIBUTION
IN UNIT 10 OF THE SHAWNEE POWER PLANT
JUNE 1970
prepared by
B. J. MATTHEWS and R. F. KEMP
UNDER NAPCA CONTRACT CPA 70-4
TRW REPORT NO. 14103-6001-RO-00
TRW
SYSTEMS GROUP
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FOREWORD
This is the final report on the "Holographic Determination of Injected
Limestone Distribution in Unit 10 of the Shawnee Power Plant. 11 Work
reported in this document was sponsored by the National Air Pollution Con-
trol Administration of the Department of Health, Education and Welfare.
This report is submitted by TRW Systems Group, TRW Inc., in accordance
with the provisions of NAPCA Contract CPA 70-4.
Work on this contract was accomplished by personnel of the Science
and Technology Division of TRW Systems Group. The Project Manager
was Mr. B. J. Matthews. Dr. R. F. Wuerker served as Consulting
Principal Scientist. Mr. R. F. Kemp was a participating Staff Engineer.
Technical administration of the contract was by Mr. D. K. Felton of the
NAPCA Division of Proces s Control Engineering.
The authors wish to acknowledge the work and cooperation of the
following TRW Systems personnel: Mr. D. E. Gallagher who ably assisted
in both the early laboratory experiments at TRW as well as the test pro-
grams at the Shawnee Unit 10 boiler; Mr. R. J. Chouinard who provided
valuable assistance in readying the pulsed ruby laser for use at the boiler;
and, Mr. J. P. Mark who helped in the fabrication of mechanical com-
ponents for the holocamera. The conduct of testing at the Tennessee
Valley Authority's Shawnee Power Plant was aided materially by a number
of persons. In particular, the coordination and assistance provided by
Messrs. D. T. Clay of NAPCA, and T. D. Womble, E. L. Sanderlin and
R. C. Tulis of TV A proved invaluable.
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CONTENTS
1.
IN TROD UC T ION. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Shawnee Unit 10 Boiler. . . . . .. .............
1.2 Dry Limestone Injection Process . . . . . .
1. 3 Holographic Determination of Injected
Linestone Plumes. . . . . . . . . . . . . . . . . . . . .
2.
PR OG RAM SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Calibration Studies-Phase I.................
2.2
Field Trials - Phase II and III
.......
.........
3.
E XPE RIME NT AL APP ARA T US. . . . . . . . . . . . . . . . . . . .
3.1 Pulsed Ruby Laser Illuminator. . . . . . . . . . . . . . . .
3.2 Single Beam (Gabor) Holocamera . . . . . . . . . . . . . .
3. 3 Two- Beam Holocamera. . . . . . . . . . . . . . . . . . . . .
3.4 Reconstruction Apparatus and Techniques. . . . . . . . .
3.4.1 Reconstruction of Gabor Holograms. . . . . . . .
3.4.2 Reconstruction of Two- Beam Holograms. . . . .
3.5 Recording Films and Processing. . . . . . . . . . .
4.
LABORATORY EXPERIMENTS. ......... ......
4. 1 Gabor Holograms. . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Two-Beam Scattered Light Holograms. . . . . . . . . . .
5.
SHAWNEE UNIT 10 EXPERIMENTS. . . . . . . . . . . . . . . . .
5. 1 Gabor Holograms - Unit 10 Superheater. . . . . . . . . .
5.2 Scattered Light Holograms - Unit 10 Boiler. . . . . . . .
5.2.1 Operating and Test Conditions...........
5.2.2 Data Reduction from Holographic.
Reconstructions. . . . . . . . . . . . . . . . . . . . .
6.
RES UL TS AND DISC USSION . : . . . . . . . . . . . . . . . . . . . .
6. 1 Tests Without Limestone Injection-140 MW. . . . . . .
6.2 Tests Without Limestone Injection-85 MW. . . . . . . .
6.3 Tests With Limestone Injection-140 MW. . . . . . . . .
6.4 Intensity Measurements and Calibration. . . . . . . . . .
7.
CONCL USIONS. . . . . . . . . . . . . . . . . . . . . . .
........
8.
RECOMMENDA TIONS FOR FUTURE WORK. . . . . . . . . . .
REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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CONTENTS (Continued)
APPENDIXES
A The Technique of Holography.
................
B
USAF 1951 Resolving Power Test Target. . . . . . . . .
C
Data Summary Sheets Unit 10 Limestone Injection
Test Holograms. . . . . . . . . . . . . . . . . . . . . . . ., . .
vi
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B-1
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26
ILLUSTRATIONS
1
2
3
4
5
6
7
8
9
Sketch of Shawnee Unit 10 Boiler
. . . . . . . .
. . . . . . . . . . .
Photograph of Soot Blower Port. . . . . . . . . . . . . . . . . . . .
Photograph of Row of Limestone Injectors . . . . . . . . .
Program Expenditures for 8-Month Technical Effort. . . . . .
Activity Summary Network. . . . . . . . . . . . . . . . . . . . . . .
TRW Q-Switched Ruby Laser Illuminator. . . . . .
Ruby Laser Illuminator with Cover Removed. . . . . . .
Schematic of Compact Ruby Laser Illuminator. . . . . . . . . .
Photograph of TRW Pulsed Ruby Laser Power Supply
Consoles and Tektronix 535A Oscilloscope. . . . . . . . . . . . .
Schematic of Single Beam Pulsed Ruby Laser Holocamera
Test Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Schematic of Single Beam pulsed Ruby Laser Holocamera
Arrangement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12 pulsed Ruby Laser Setup on the West Side of Unit 10 . . . . . .
13 Photograph of Shutter and Plate Holder in Front of Fort. . . .
14 Schematic of Two-Beam Scattered Light Holocamera. . . . . .
15a Plan View of Two-Beam Holocamera Installation. . . . .
10
11
1Sb Perspective View of Holocamera Installation at Unit 10 . . . .
16 Ruby Laser Illuminator Installed .Adjacent to
Unit 10 Boiler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
18
Holocamera Shutter Assembly. . . . . . . . . . . . . . . . .
Single Beam Hologram Recording and Reconstruction
Geometries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reconstruction Camera Setup for Maximum Depth of Field. . .
Single-Beam Holocamera Resolution Measurements. . . . . . . .
Helium-Neon Laser Reconstruction of a pulsed Ruby
Hologram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cumulative Volume Fraction Versus Bead Diameter. . . . . . .
19
20
21
22
23
24
25
Real Image From Hologram No.1, Series 10-8-69 . . . . . . . .
Reconstruction Photo of Stream of 40-50 Mesh Glass Beads. .
Reconstruction Photo of Stream of 40-50 Mesh Glass Beads
at 6 Feet From Hologram. . . . . . . . . . . . . . . . . . . . .
Reconstruction of Images of 40-50 Mesh Glass Beads at
12 Feet from Hologram. . . . . . . . . . . . . . . . . . . . . . .
vii
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ILLUSTRA TIONS (Continued)
27
View of Virtual Image of Low-Angle Forward Scattered
Light From Cotton Balls at 6 and 12 Feet From
Hologram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Composite Views of a Scattered Light Reconstruction.
Matrix of Shawnee Unit 10 Holographic Tests. . . . . . . . . .
Schematic of Holocamera Scene Beam Geometries. . . . . .
Collimated Scene Beam "fingerprint" on Holographic
Plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28
29
30
31
32 Densitometer Trace for Hologram No. 1331 Reconstruction
Photograph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33a Reconstruction Photo of Hologram 1381 . . . . . . . . . . . . . .
33b Reconstruction Photo of Ruby Scene Beam Light at Prism
Approximately 33 Feet From Holocamera . . . . . . . . . . . .
34 Densitometer Trace for Hologram 1564 Reconstruction
Photograph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35 Densitometer Traces From a Mapping of Hologram 1570
Projected into a Composite Perspective. . . . . . . . . . . . . .
36 Photograph of Reconstructed Virtual Image of Fan Beam
Scattered Light From Hologram 1570 . . . . . . . . . . . . . . .
viii
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1.
INTRODUC TION
The dry limestone process of removing sulfur oxide from power
plant stack gases is one of several methods currently under investigation
by the National Air Pollution Control Administration (NAPCA). Full-scale
testing and evaluation of this proces s is, at this time, being conducted at
the Unit 10 boiler of the Tennessee Valley Authority's (TV A) Shawnee
Steam Plant located outside of Paducah, KentuckyJ, 2, 3 This report is
concerned with the application of pulsed ruby laser holography as an instru-
mentation technique for detecting the penetration and dispersion of lime- *
stone plumes injected into the Unit 10 boiler operating at nominal conditions.
1.1
SHA WNEE UNIT 10 BOILER
The test boiler at the Shawnee plant is a pulverized coal, front-fired
unit which, during the holographic studies, was operated at a nominal
electrical power output of 140 megawatts. At this power output, Unit 10
burns approximately 56 tons of pulvarized coal per hour injected into the
furnace through 16 individual burners. The amount of air consumed in the
combustion proces s (at the nominal output) is in the order of a million
pounds per hour.
The holography experiments were conducted at an elevation of 364
feet, 9 inches using one of the limestone injection ports on the north side
and an unused soot blower port on the south or front side of the boiler.
Flame temperatures in this general vicinity are in excess of 25000F
resulting in a high black body (yellow) luminous output. Combustion gas
velocities are estimated to range from 30 to 60 ft/ see at the 365-foot
elevation. A perspective sketch, shown in Figure 1, illustrates the gen-
eral arrangement of the Unit 10 boiler as well as pertinent port locations.
In Figure 1, it will be seen that the internal distance between the
front (south) and rear (north) water walls of the boiler is 24 feet at the
365-foot elevation. The internal width (east to west) of the boiler is 46
feet. Not shown in this sketch is a boiler division wall which divides the
46-foot width in half. Note that the main or ground floor of the Shawnee
plant is at an elevation of 345 feet. Details of the boiler below that eleva-
tion are not shown in Figure 1. The photographs of Figures 2 and 3 show
the viewing ports used in the holocamera test setup. Figure 2 illustrates
the unused soot blower port (elevation 365) on the front side of the boiler.
Figure 3 shows the limestone injection port on the rear side of the boiler
at elevation 364 feet, 6 inches. During the holography experiments, the
limestone injection tube was removed from the port.
*The holographic studies described in this report were conducted under
provisions of NAPCA Contract CPA 70-4 in support of the overall dry
limestone process evaluation program.
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. OBSERVATION DOOR
(6" X 12")
-$- SOOT BLOWERS
. OBSeRVATION OOOR
(1rxW)
-$-- LIMESTONE INJECTORS
.. HOLOGRAPHY PORT
NOTE. DIVISION WALL DIVIDES UNIT EQUALLY IN N.S DIRECTION.
. BOILER WALLS ARE Ii; MEASUREMENTS.
Figure 1.
Perspective sketch of the Shawnee Unit 10 boiler
showing basic dimensions and port locations
The injection of limestone is accomplished through a total of 16
injection ports. The ports are. located at three different elevations on the
boiler. Four of the limestone injectors are located at an elevation of
359 feet, 9 inches on the south or front side of the boiler. All of the re-
maining 12 limestone injectors are instalted on the rear (north) side of the
boiler with six located at the elevation 347 feet, 6 inches and six more at
elevation 369 feet, 6 inches. Injection of the limestone is accomplished
pneumatically. During the holography experiments, described in Sections
5 and 6 of this report, the limestone injection flow rates varied between
1000 and 2750 pounds per hour for individual ports. At the point of injec-
tion into the boiler, approximately 70 percent of the limestone is les s than
200 mesh (74 micron diameter) size. In contrast, measured fly ash samples
(collected at the stack precipitator) reveal that 80 to 95 percent of the fly
ash is less than approximately 30 microns in diameter.
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Figure 2.
Figure 3.
II
I
I
I
JI
,~;:'
i~
-
Photograph of soot blower port on south side of Unit 10
used for holography tests (elevation 364 feet, 6 inches)
.
: .~
Photograph of row of limestone injectors at elevation
364 feet 9 inches on north side of Unit 10. For holo-
graphy tests, the injection tube was removed from
near port.
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1. 2 DRY LIMESTONE INJECTION PROCESS
In the drlT limestone process under evaluation at ShawtnheeU' ~itn1eOlY
7 . 11 . . t d into e nl
ground limestone particles are pneumahca y 1nJ~c. e. . t the boiler
boiler at one or more of three elevations. UP?n ~nJectlon In 0 el throu h
combustion gases the particles sorb sulfur diOJade as they trav g
the furnace. Although the sorption process is complex ~nd not completely
understood, the following reactions are usually assumed:
(1)
CaC03 + Heat -+ CaO + C02
( 2)
CaO + S02 + 1/202 -+ CaS04
During the initial calcination, carbon dioxid~ is removed to make
room for the sulfur dioxide and the limestone parhcle becomes porous.
This porosity results in an increase in particl.e s~J.rf~ce area and p~o-
motes a more rapid reaction with the sulfur dIoxIde In the .combustio~ .
gases. The reaction temperature and particle residence ~1~~ are c~lt1c.al.
A temperature in the order of 20000F is required for the lnltlal. calcInation
of the limestone particles. The optimum temperature for the hme sulfa-
tion reaction is thought to be approximately 1900oF. 5
1. 3 HOLOGRAPHIC DETERMINATION OF INJECTED
LIMESTONE PLUMES
Of primary concern to the full-scale evaluation of the dry limestone
injection proces s is the degree of limestone plume penetration, dispersion
and continuity. Holography was selected as a candidate instrumentation
technique for two reasons. Perhaps the most significant reason is that
passive in situ measurements are possible with holography, hence, the
recorded quantity is not compromised by remote sampling procedures or
the introduction of foreign mechanisms or probes. Also of importance is
the fact that holography permits the recording of a volume of information
as opposed to more limited methods such as point sampling. Accordingly,
an 8 -month program was initiated in August 1969, to demonstrate the
feasibility and utility of pulsed ruby laser holography for recording injected
limestone plumes in the Shawnee Unit 10 boiler.
The holography program, sponsored by NAPCA under contract CPA
70-4, consisted of three phases. During Phase I optical components for
a single-beam (Gabor) holographic arrangement were designed, fabricated
and assemble for calibration tests. The single-beam holography tests
consisted of resolution measurements over distances comparible to the
dimensions of the Unit 10 boiler (elevation 365) and superheater (eleva-
tion 392) where subsequent field trials were to be conducted. In addition
to the single-beam holographic tests made during Phase I, a modified two-
beam system was developed and demonstrated. The two-beam holographic
arrangement was unique in that objects within the scene volume were not
imaged directly onto the photographic plate (hologram). Instead, low
angle forward components of the light scattered by objects within the laser
scene beam were recorded by the hologram.
-------
Although the two- beam holographic technique was ultimately selected
to record portions of the limestone plumes injected into the Unit 10 boiler,
considerable work was done in the area of Gabor or single-beam holography.
Gabor holography appeared attractive from the standpoint of overall simplic-
ity and the need for installation of only a minimum number of components on
the boiler. For these reasons, a Phase II feasibility demonstration trial at
the Shawnee Unit 10 superheater (elevation 392) was implemented. The
single- beam technique proved inadequate to the task of recording large
ensembles of particulate in the superheater because of heavy attenuation of
the las er light. Holographic studies continued, however, with the initiation
of Phase lIT and employment of the alternate two-beam holographic technique
developed during Phase I. The subsequent Phase III tests were conducted at
the 365-foot elevation of the boiler. Holographic recordings of light scatter-
ing caused by the presence of limestone clouds or plumes were successfully
made. The final portion of Phas e III was devoted to developing means of
acquiring and evaluating limestone plume data.
Financial expenditures (excluding fee) for the 8-month technical effort
for the holography program are shown in Figure 4. The technical activities
associated with each of the three phases of work are presented in the event
logic network of Figure 5. This latter figure also shows the sequence of
reports submitted during the 8-month technical effort as well as the prepar-
and 3.lbmittal of this final report.
100
90
V) 80
o
Z
« 70
V)
::J
0 60
:r:
I-
Z 50
V)
OI!
« 40
....J
....J
0
0 30
20
10
o
AUG
TOTAL COST
OF$91.6K
(EXCLUDING FEE)
0-1 COMPLETE
0-11 COMPLETE
0-111 COMPLETE
SEP
NOV
DEC
JAN
FEB
MAR
OCT
Figure 4.
Program expenditures for 8-month
technical effort
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Figure 5. Activity Summary Network
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2.
PROGRAM SUMMARY
The three-phase holography program to make in situ recordings
of injected limestone plumes in the Shawnee Unit 10 boiler is conveniently
discussed in terms of the initial calibration studies made at TRW Systems
Group in Redondo Beach, California, and the subsequent field trials at
the Shawnee Steam Plant in Kentucky.
2.1 CALIBRATION STUDIES-PHASE I
The Phase I calibration studies at TRW Systems were initiated in
August 1969. This work included the preparation of holographic equip-
ment and the experimental verification of techniques for later use at the
Shawnee facility. A major effort was directed toward utilizing a single-
beam (Gabor) holographic arrangement to record particulate in the super-
heater region (elevation 392) of Unit 10 during Phase II. There was,
however, concern that the expected large quantities of fly ash and injected
limestone particulate would attenuate the probing ruby laser beam to the
extent that single-beam holography would not be feasible.* For this reason,
a two-beam holographic arrangement was designed to overcome this anti-
cipated problem area. Although somewhat more sophisticated in concept,
this alternate technique was later used (in Phase ill) when the single-beam
method subsequently proved inadequate.
Work during Phase I with both the Gabor and the two-beam methods
of holography resulted in several significant achievements. Although the
single- beam method was eventually discarded in favor of the two-beam
system., a considerable amount of testing was accomplished representing
an extension of previous technology. For this reason, the single-beam.
holography results are discussed at length in this report in the belief
that this work may provide insight for possible future applications.
Modification of a conventional two-beam holographic arrangement to
allow the recording of low-angle forward- scattered light is the most
significant aspect of the calibration studies of Phase 1. Development of
this technique led to the successful recording of limestone plumes in the
Unit 10 boiler during Phase ill. The pulsed ruby laser holography work
and accomplislunents of the calibration studies are sununarized as
follows:
.
Components were fabricated and assembled into a
single- beam holographic arrangement suitable for
''long distance" holography.
Single- beam. holograms of resolution targets and dis-
persions of glass beads were recorded at intervals
of 6 feet from the holographic plate over distances in
excess of 48 feet. This is the first known work with
Gabor holography at these extreme object distances.
.
>:
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. Single-beam holographic resolution meas,?,remen.ts at an
object distance of 6 feet yielded a ~esolutl.on ~qulvalent
to particles of approximately 50 mlcr.on~ m Slze. At
50 feet the resolution measurements mdlcated that
particles of only 550 microns could be resolved.
. From the single-beam recordings of glass beads (40 to
120 mesh) it was demonstrated that discrete bead
images could be distinguished up ~o dista~ce.s of 12 feet.
Beyond this distance, reconstructlon of dlstlnct bead
images was difficult. When the distance exceeded 18 feet,
individual bead images were not discernible.
. Using a reconstructed holographic recording of 40 to 50
mesh glass beads located a distance of 6 feet from the
film plate, it was demonstrated that individual bead
images could be measured and a size distribution deter-
mined from the measured data.
. A two-beam holographic arrangement was developed to
record light scattered at low angles in the forward
direction over distances up to 50 feet. A series of
"scattered light holograms" of various objects located
in the scene volume were recorded to demonstrate the
feasibility of this new technique.
. A ranging telescope was built, calibrated and subsequently
used to demonstrate that two-beam holographic images of
scattered light could be brought into focus. Distance
measurements along the laser beam axis to the edges of
the scattered light image were possible and, therefore,
the position of the image within the recorded scene could
be measured.
2.2 FIELD TRIALS - PHASE II AND III
Phase II of the program was accomplished during December 1969.
The TRW pulsed ruby laser and holographic equipment were shipped to
the Shawnee Steam Plant in Kentucky. The apparatus was installed on
the Unit 10 superheater at the 392-foot elevation. Gabor holograms of
fly ash distributions across the 50-foot-wide superheater were attempted.
Twenty-nine recordings were made; however, no meaningful reconstruc-
tions were obtained. Further attempts to utilize single-beam holography
were abandoned. It was concluded that the severe attenuation and multiple
scattering by the particulate in the stack gas encoded the single beam of
coherent light sufficiently to prevent making holograms which could be
reconstructed.
A program review of the initial two phases of work led to a de~ision
in January 1970, to concentrate on adapting a two-beam holographic sys-
tem for recording injected limestone plumes in the Unit 10 boiler. Equip-
ment modifications were completed at TRW Systems and the Phase III
field trials begun at the Shawnee plant in February 1970. The holocamera
apparatus was installed at a boiler elevation of 365 feet. Details of the
installation are presented in Section 3.3 of this report.
-------
During the 3-week Phase III effort, 79 holograms were recorded
both with and without limestone injection into the boiler. Data reduction
and evaluation of results were accomplished on 25 of these successful
holographic recordings. The significant achievements of Phase III work
may be sununarized as follows:
.
The successful recordings obtained during field trials at
Shawnee represent the first major application of holography
to the study and monitoring of an industrial process.
.
Using the innovation of scattered light holography, the
presence of limestone plumes in the boiler was detected.
The recordings yield instantaneous scattered light images
possessing excellent three-dimensional qualities.
. A hologram recording rate of one plate per minute was
achieved using manual methods. Although each recording
provided an instantaneous increment of data, repetitive
recordings allow the evaluation of time changes in the
lime stone plume phenomena.
.
Photometric techniques were developed to obtain quantita-
tive information from the developed holograms concerning
the penetration of the limestone plume into the boiler,
dimensions of the plume (along the laser beam axis) and
the presence of voids or gas bubbles in the plume.
.
Excellent correlation was established between the dimen-
sional data obtained with the photometric measurements
and those acquired directly using the calibrated ranging
telescope to observe the scattered light images in the
hologram. .
In addition to dimensional plume data, an indication of
limestone plume density was obtained from the relative
light intensity measurements made via the photometric
studies. An approach to determining absolute light
intensity values from the reconstructed hologram images
was conceived which would allow estimates of particle
number concentrations of limestone during future holo-
graphic studies.
In summary, the feasibility of using holographic techniques to make
in situ recording of limestone clouds or plumes in a full- scale operating
steam boiler was demonstrated. Techniques were developed to analyze
the resulting holograms and acquire quantitative data. This final report
describes the experimental apparatus used, the laboratory experiments
and the test program conducted at the Shawnee plant. These discussions
are presented in Sections 3 through 5, respectively. A discussion of the
results obtained during the Phase III field trials with scattered light
holography is presented in Section 6. Conclusions and recommendations
follow in Section 7 and 8.
.
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3.
EXPERIMENTAL APPARATUS
3.1 PULSED RUBY LASER ILLUMINATOR
The source of illumination for the holocamera apparatus was a
pulsed ruby laser system designed and built at TRW ~yst~ms Group.
Photographs of this solid state ruby laser are shown In FIgures ~ and?
The laser emits 1 to 3 joules of 0.6943 micron wavelength (red hght) m
pulses of 30 to 50 nanoseconds duration. The temp?ral c?h~renc~ of the
laser was not measured; however, from past experIence It IS beheved to
be about 5 centimeters.
A schematic diagram, Figure 8, shows a plan view of the components
in the ruby laser. Included in the package are a "folded" arrangement of
the oscillator-amplifier Q-switched ruby laser, a monitor diode, a dark-
field alignment autocollimator and a helium-neon directional pointing gas
laser. Switching of the optical path among these components is accom-
plished by a arrangement of reflectors operated by the small round knobs
on top of the laser cabinet (Figure 6). Reference to Figure 8, and the
photograph of Figure 7 illustrates the internal optical path of the laser and
the various components of the system. 6
The laser power supply and control electronics are housed in sepa-
rate consoles as seen in Figure 9. The right-hand console contains two
ignitron-fired 0 to 5 kv, 375 fJ. F capacitor banks used to energize the
helical Xenon flash lamps in the ruby oscillator and amplifier assemblies
of the laser. The companion console contains the independent high voltage
supply and control circuits for the Kerr cell Q-switch. Also shown in
Figure 9 is a Tektronix Type 535A oscilloscope used to record the ruby
oscillator output energy monitored by the integrating photodiode.
3.2 SINGLE BEAM (GABOR) HOLOCAMERA
At the beginning of this study (Phases I and II), Cabor holography
was tested as a means of detecting limestone clouds. It did not prove
feasible; however, a sufficient amount of work was accomplished using the
Gabor technique to warrant a description of the apparatus. A brief sum-
mary of results using single - beam holography is given subsequently in
Sections 4.1 and 5. 1.
Gabor holography employs a single-beam of coherent light which is
typica.lly passed through a scene and allowed to fall directly on a photo-
¥raph1c plate. The plate records the intensity distribution caused by the
mterference between the beam transmitted through the scene and the light
scattered by objects in the beam. Although only a single beam is used,
the photographic plate records the superposition of two wave fronts: the
transmitted and the scattered light wave fronts. *
*
The fundamental technique of holography is discussed in Appendix A.
-------
Figure 6.
TRW Q-switched ruby laser illuminator
r -..- -
",.
,(
w;
JA RUBY I
;'fP.J<:llL.ATO!!J
~
t
~
I.
I
--
---
{;
L
Figure 7.
Ruby laser illuminator with cover removed
to show location of major components
-------
MIRROR
M4
AUTOCOLLIMATO~
COLLIMATOR
OUTPUT PORT
.....
~
PRISM
OUTPUT
RESONANT
REFLECTOR
Figure 8.
RUBY ROD
AN D FLASH LAMP
HOUSING, AMPLIFIER
-----
53 Y2IN
cw
He Ne LASE R
!
i LASER
------I----oUT~--
i
!
!
RUBY ROD
AND FLASH lAMP
HOUSING
OSCILLATOR
POLARIZING
PRISM HOUSING
Schematic diagram of compact ruby laser illuminator
.
PERISCOPE
PRISM
/
RESONANT MIRROR
ADJ. KNOBS
99% DIELECTRIC
-------
Figure 9.
Photograph of TRW pulsed ruby
laser power supply consoles and
Tektronix 535A oscilloscope
The simplicity of a single beam or Gabor holographic test setup is
shown in Figure 10. Such a test arrangement was used at TRW'Systems
to conduct laboratory measurements of resolution as a function of object
distance d from the holographic plate. Results of these measurements
are presented in Section 4.1. The Gabor setup has the further feature
that it is almost insensitive to the temporal coherence of the ruby laser
illuminator.
CAMERA
HOUSING
Q-SWITCHED RUBY LASER
(OUTPUT = 1-3 JOULES IN
30-50 NANOSEC. PULSE)
\
DIVERGING TEST OBJECT FOCAL
LENS i PLANE
. SHUTTER
~:::~ "0."" : = :
5 INCH COLLIMATING LENS L.-J
(OBJECT DISTANCE) I
HOLOGRAM
PLATE
~I
PHOTODIODE
TO MONITOR
LASER PULSE
Figure 10.
Schematic diagram of single beam (Gabor)
pulsed ruby laser holocamera test setup
-------
The illuminator was a Q-switched ruby laser (X. = 0.6943 micron)
which provided a 30 to 50 nanosecond pulse of 1 to 3 joules content. From
Figure 8, it can be seen that typically a i-centimeter (0. 394-inch) diameter
beam from the ruby laser was expanded by a small diverging lens and then
collimated with a 5 -inch-diameter, 24.75 -inch-focal-length lens. >',< A test
object was located in the scene light a predetermined distance from the
hologram plate. During laboratory experiments, the test object was a
USAF 1951 resolution target or a fine spray of titanium glass beads. The
overall distance from the hologram plate, located in the" camera housing, "
to the output (collimating) lens of the laser system was about 55 feet.
Subsequent Unit 1 0 Gabor holography tests utilized a test setup com-
parable to that just described. A schematic of equipment placement and
pertinent dimensions is shown in Figure 11. Photographs of the pulsed
ruby laser and camera shutter mechanism placed before the superheater
(elevation = 392 feet) are presented in Figures 12 and 13.
2'6"-,
FilM --
PlA NE r.lI
Il,J
CAM"A /
HOUSING
47'2"
57'0" ~
- 7'4" / 4 IN. DIA. COLLIMATED BEAM,
A = 0.6943 1J
5" x lB" DOOR
/ / ,/ RUBY lASER
" I
4" DIA. PORT. D- H20
COOLER
UNIT 10 SUPERHEATER
ElEVATlON,392FT.
D--OSClllOSCOPE
D,..---:: CONTROL
ELECTRONICS
D.
o - 5 KV
POWER
SUPPLY
SUPERHEATER ~
WAll --
NORTH BlDG /
WAll
Figure 11.
Schematic diagram of single beam
pulsed ruby laser holocamera
arrangement used on the Shawnee
Unit 10 boiler superheater
Th~ ruby ~raser was located on the west side of the Unit 10 super-
heate: wIth t~e camera" located on the far side of the boiler directly
OpposIte. Ahgnment of the ruby laser, with the 4-inch-diameter boiler
port~ and the camera was accomplished visually using the beam from a
contInuous wave helium-neon gas laser bore sighted to the pulsed ruby
laser beam. The gas laser was mounted in line and directly over the
,t.
'0' Jaegers lens No. 3E 1475.
-------
Figure 12.
Pulsed ruby laser setup on the west side
of the Unit 10 superheater for Phase II
Gabor hologram recording tests
Figure 13.
Photograph of shutter and plate
holder placed in front of port on
east side of Unit 10 superheater
for Phase II tests
-------
pulsed ruby lase.r. Two mirrors were used to sub~e.quently direct the
helium-neon gas laser beam through the ruby ampllfler and then along the
optical path of the pulse laser. *
With the gas laser operating, the ruby laser housing position was
adjusted (using wedges) until the helium-neon ~ea~ passed through th.e
opposed 4-inch-diameter boiler ports a~d. wa~ mCIdent o~ the 4 by 5 -mch
format of the hologram film plate. VerIfIcatlon of the alignment was later
made by observing the ruby laser optical pulse through a ground glass plate
installed on the camera housing. Additional alignment checks were made
with Eastman SO-243 cut film loaded in the camera back.
The camera consists of a holographic film plate holder, two shutter
mechanisms and provisions for holding a Wratten No. 70 red gelatin filter
to prevent fogging of the plate by flame or other extraneous light. The
primary shutter was an adaptation of a focal plane shutter mechanism
from a Graflex camera. The shutter is manually cocked against a preset
spring tension using the large knob on the left-hand rear side of the camera
assembly (Figure 13). Activation of the focal plane shutter is accomplished
using a 28 vdc solenoid. A microswitch on the shutter winding shaft senses
the open position of the focal plane shutter and remotely triggers the pulsed
ruby laser. The nominal open time of the focal plane shutter is approxi-
mately 50 milliseconds during which the 50-nanosecond laser pulse occurs.
The secondary II capping" shutter is also operated with a solenoid. This
slow acting shutter is opened a convenient time prior to activation of the
focal plane shutter and closed after the holographic recording has been
made.
3.3 TWO- BEAM HOLOCAMERA
The Phase III holography studies conducted at the 365 -foot elevation
of Unit 10 utilized a two-beam transmission holocamera designed to record
not the direct transmitted beam but instead, low angle forward scattered.
light. The two-beam holocamera differed from the Gabor setup in that the
reference illumination was physically removed from the scene volume and
passed around the outside of the boiler with the use of additional optics.
The reference illumination, termed the II reference beam" is incident on
the holographic plate in an unmodified state. As such, it is readily dupli-
cated and facilitates reconstruction of the developed plate.
~pp~ication .of a two.- beam holograp~ic technique proved absolutely
essentlal In studymg particulate matter dIspersed over large distances in
the operating boiler.. Thermal gradients, some indication of turbulence
*
The ruby laser used during the superheater test program was identical in
function but different in form from the one described in Section 3.1. This
earlier laser was a laboratory model provided by the Physical Electronics
Laboratory of TRW. It was subsequently replaced by the newer illuminator
described in this report.
-------
and the presence of large ensembles of particles, heavily attenuated the
laser light (scene beam) passing through the boiler. Single-beam or
Gabor holography is dependent upon a portion of the illumination passing
through the scene in an unmodified state. This unmodified portion of the
illumination serves as the reference beam which, when duplicated, recon-
structs the recorded scene. In the case of the boiler studies, the heavy
attenuation and modification of the laser beam encoded all of the illumina-
tion making it impossible to produce a meaningful reconstruction.
The two-beam holocamera configuration eventually selected for work
at the boiler is a modification of more conventional transmission holo-
camera arrangements. The particles contained within the recorded scene
volume are not imaged directly onto the holographic plate. Rather, the
presence of particles in the scene is detected by scattered light.
Verification of the low angle forward scattered light holocamera
technique was first accomplished under the separate sponsorship of the
TRW independent research program. The holographic arrangement used
during these early tests is shown schematically in Figure 14. The
arrangement utilized a 5 -inch-diameter collimating telescope, two front-
surface mirrors, a glass wedge beam splitter and a corner prism. The
light beam from the pulsed ruby laser was directed through the beam
splitter and corner prism and projected across a scene volume of approxi-
mately 45 feet. The unexpanded scene beam was purposely directed so
as not to impinge on the holographic plate. The wedge beam splitter
diverted about 4 percent of the light energy into the collimating telescope
to form the 5 -inch-diameter reference beam. The reference illumination
was directed around the scene volume. The two front-surface mirrors
directed the beam onto the hologram plate at an angle of nearly 10 degrees.
In contrast, the scene beam (as seen in the diagram of Figure 14) consisted
only of that portion of the light scattered at a low forward angle from
objects placed to intercept the unexpanded laser beam. The technique is
relatively independant of the temporal coherence of the ruby laser.
WEDGE BEAM
SPLITTER
HOLOGRAM
SCATTERED BEAM FROM PARTICLE ~
PARTICLE FielD ~ -- -- - -- . --~----
~~~~~?~~-::~~.:~~-- .-
SCENE BEAM ... ..:.~:=:-r.-:- --- --
--
CORNER
REFLECTOR
FRONT SURFACE MIRROR
SCENE BEAM STOP
PULSED RUBY LASER
Figure 14.
Schematic diagram of two- beam scattered light holocamera
-------
The apparatus described above was used to demo~strate the f.easi-
bility of recordip.g forward scattered light on holographIc plates uSIng .a
conventional Q-switched ruby laser. A series of tests was conducted In
which scattered light from tufts of cotton, glass fibers and c?alk ~ust was
successfully recorded. The results of these tests are. descrl~ed In .
Section 4. Verification of the technique led to the desIgn and Installation
of a scattered light transmission holocamera at elevation 365 feet on the
Unit 10 boiler.
The holocamera optical component arrangement for the Phase III
tests at elevation 365 feet on Unit 10 is shown in the plan view diagram of
Figure 15a. The pulsed ruby laser illuminator for the holocamera was
installed on a shelf positioned approximately 8 feet above the ground floor
elevation of 345 feet. This installation is shown in Figure 16. The prox-
imity of the laser to the boiler and holocamera components is shown i~
Figure 15b which is a perspective drawing of the test setup. From thIs
illustration, it is seen that light was passed from the laser source to the
beam splitter box (refer to Figure 15) by means of a periscope arrangement.
The laser input beam was directed into a horizontal plane at the
desired boiler port elevation (....365 feet) by the periscope. The beam next
entered the first optical package which consisted of a prism (No.3), wedge
beam splitter assembly and a collimating telescope. Referring to Fig-
ure 15, it will be seen that a portion of the laser input beam passed through
the beam splitter assembly and proceeded directly across the front (south)
side of Unit 10 to a prism box placed before the inlet port of the boiler.
The laser beam is directed by the final reflector (prism No.4) so as to
enter the boiler and traverse the 24 feet of combustion volume. This last
prism was set so that the light just missed the exit port on the far side or
rear north walt. As in the Figure 14 test configuration, the laser beam
did not fall directly on the holographic plate. Particles within the illumi-
nating beam scattered light from the beam. Some of the light scattered at
low angles in the forward direction emerged from the rear port and fell on
the holographic plate to form the scene beam.
The reference illumination is formed by reflecting a portion of the
laser light at the wedge beam splitter (Figure 15). The reference beam is
passed thr Ollgh a negative lens and expanded to a 5 -inch-diameter and then
collimated. With the reference beam expanded to illuminate the holographic
plate, it is passed by two front surface mirrors to the plate at an angle of
15 degrees with respect to the nominal axis of the emerging scene light.
The angle of separation between the scene and reference beams is not
critical. A design value of 10 to 30 degrees was selected as providing
adequate viewing angle separation (on reconstruction) and at the same time
simplify the tasks of camera and mirror mounting and of matching the
optical path lengths of the scene and reference beams.
The camera and shutter assembly shown in Figure 17 is designed to
accept standard 4 x 5 photographic film or plate holders. As described
earlier in Section 3.2, it is fitted with two mechanical shutters, a slow-
acting capping shutter which helps to protect internal parts from dust and
-------
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Figure 15a.
Plan view of two- beam holocamera
installation at elevation 365 feet
ELEV 365
~
LlMESTO Nf
INJECTION PORT
SOUTH WAll
ELEV 359' - 9"
NORTH
1~'::1
4;-1
1~1
~ ,."
1%,1'
~
EXPANDING AND
COlLIMATING OPTICS
WEDGE BEAM
SPLITTER
CORNER PRISM
~
I
.
PERISCOPE
GROUND flOOR 0 HEV 34S
Figure 15 b.
Perspective view of holocamera
installation at Unit 10
-------
Figure 16.
View of ruby laser illuminator
installed adjacent to Unit 10
boiler at elevation 353 feet
(approximately)
.
..
Figure 17.
Holocamera shutter a.ss~~p~y;
-------
radiant heat, and a fast-acting "focal-plane" shutter. Each time an
exposure is to be made, the following sequence of events is typical:
.
The film holder is loaded into the shutter mechanism, and
the dark slide pulled.
.
The laser flashlamp capacitor banks are charged.
The capping shutter is opened by energizing its electrical
solenoid.
.
.
The focal-plane shutter is tripped by energizing its
solenoid. A microswitch operated from a cam on the
focal-plane shutter mechanism sends a trigger pulse
to the laser power supply at the instant the focal-plane
shutter is fully open. Laser flash duration is approxi-
mately 50 nsec; total exposure of the film to flame light
is approximately 50 msec before the focal plane shutter
is completely closed again.
.
The dark slide is replaced and the exposed film is either
removed to the dark room for processing or stored for
later processing.
3.4 RECONSTRUCTION APPARATUS AND TECHNIQUES
The scene volume recorded by a hologram is recreated or "recon-
structed" by setting the holographic plate before a coherent monochromatic
light source and illuminating it with a beam which closely duplicates the
original reference illumination. To achieve the most accurate results,
the original reference beam must be duplicated as nearly as possible with
respect to wavelength and angle of divergence. A convenient continuous
wave (CW) illumination source for reconstructing pulsed ruby laser holo-
grams is a helium-neon gas laser which emits at a wavelength of
O. 6328 micron. A Spectra-Physics Model 124 helium-neon gas laser of
approximately 15 milliwatts power output is quite adequate for the task.
Although there is a 1. 0 percent difference in wavelength between the pulsed
ruby laser (X, = O. 6943 micron) used to record the holograms, and the
helium neon gas laser employed to reconstruct the scene, careful adjust-
ment of beam divergence angle and orientation of the holographic plate
before the reconstructing beam can eliminate or greatly minimize astigma-
tism and distortion.
When the developed holographic plate is properly illuminated in the
reconstruction process, a virtual image of the recorded scene is observed
behind the plate in the same physical location as the original scene. The
holographic plate becomes a window through which the virtual image of the
scene may be observed visually or with the aid of magnifying optics. A
convenient means of obtaining a permanent reconstruction record is to
photograph the virtual image. This technique was used to evaluate and
reduce data contained in holograms recorded on the present program.
-------
3.4.1
Reconstruction of Gabor Holograms
The simiiarities and differences between the recording and recon-
struction geometries for single - beam holograms are illustrated in
Figure 18. The hologram is formed as a recording of the stationary inter.
ference pattern between the collimated laser beam of wavelength ~ and the
diffracted light from the object at a distance d from the plate.
Upon illumination of the hologram with a collimated light beam of
wavelength X, four "beams" emerge from the hologram plate: (1) undevi-
ated rays from the reconstruction beam, (2) "noise" rays from defects in
lenses or in the hologram plate as well as from nonlinear and intermodu-
lation effects, (3) diverging rays from the virtual image of the hologram,
and (4) converging rays which come to a focus at some distance d1 from
the hologram plate, forming a real image. If ~ = X, the focal distance d1
will equal d also. The real image at d1 can be observed by placing a view-
ing screen at that location, or it can be recorded directly on film. An
auxiliary optical system (camera, eye, microscope or telescope) placed in
the beam as shown in Figure 18 will form subsequent real images on film
retina or other sensitive material. '
LASER
DIFFRACTED LIGHT
FROM OBJECT POINT
COLLIMATING LENS J...- -- HOLOGRAM PLATE
t---~-::::.
p-r --- .......- A ~ ~ ~ .:=- -
--- -A~ - --
-- ...:::::-------
~-
DIVERGING LENS " ......
OBJECT
A. RECORDING
d
FOCAL PLANE OF
REAL IMAGE
HOLOGRAM \ ~ DIVERGING RAYS CAMERA
DIVERGING OF /
LENS -- -~--_.___~VIRTUAL IMAGE
~.........:4 ~-- - -- ---
/' -~-- - - ...--
LASER p_T1:: 0 A'l::=--:::.~;-:.~ -..::.-='=-==~-= -'~"::--'-....r:---- } ILLUMINATED
U ........ ---=-... -=-::-----------.. ----=~- ----
~ -- ~:;;:..=:.:- -~~="'---- .r::=;"-~::: AREA
""'<.;:----- ------
COLLIMATING / L~--~--
LENS
B. RECONSTRUCTION d]
Figure 18.
Single - beam hologram recording and
reconstruction geometries
-------
3.4.2 Reconstruction of Two-Beam Holograms
The technique of reconstructing the two- beam holograms recorded
during Phase III of the program is similar to that just described for the
Gabor holograms. With single-beam or Gabor holograms, the scene and
reference illumination are on a common axis. With the two- beam holo-
camera arrangement reported in Section 3.3, there is a separation in
viewing angle between the scene and reference beams of 15 degrees. The
viewing angle within the scene was limited by the size of the boiler viewing
port to about 3 degrees. There is no overlap or confusion between refer-
ence and scene beams in the two-beam holograms.
To view the developed holographic plates made with the two- beam
holocamera, it was necessary only to illuminate the plate with a CW gas
laser beam which had been expanded and collimated to a diameter of
approximately 5 inches and then to orient the plate at the proper angle with
respect to the incident beam. In this manner, the entire plate is illumi-
nated, and it is possible to view the recorded scene with full binocular
perspective.
One of the unique characteristics of all of the holograms recorded
during the program was the extreme length of the scene volume. During
the Phase III tests at elevation 365 feet, the effective scene depth of field
was 24 feet. In reality, the actual depth of field was greater since the
holographic plate was physically located some 33 feet away from the
corner prism on the far side of the Unit 10 boiler. To locate and measure
axial distances to images within the scene volume, a range finding tele-
scope was used. A medium power lIastronomical" telescope was placed
before the reconstructed hologram to observe the virtual image. Image
distances could be read directly from a calibrated scale located on the
focussing tube of this instrument which mapped the image field from 4 feet
to infinity into a 4-inch scale.
To use the telescope distance measuring technique properly, the
divergence angle of the reconstruction beam must be precisely set; other-
wise, objects appear to focus at the wrong distance from the telescope.
The easiest way to make this adjustment is to use the telescope as a
standard. The laser and its expanding telescope are positioned to illumi-
nate the hologram. The viewing telescope is then positioned to view the
image, with the telescope at a fixed distance (say, 3 or 4 feet) from the
hologram plate. This distance is added to the known distance from the
hologram for the furthest visible object in the scene (in this case, the
prism at the front of the boiler which deflects the scene beam for the last
time, 33.25 feet from the hologram plate), and the focus scale is set to
this value. The corresponding object is then brought into focus in the
viewing telescope by adjustment of the focus of the expanding telescope on
the laser. All scene distances as measured by the viewing telescope are
then to scale.
Much of the data acquired from the limestone plume holograms of
Phase III necessitated the production of a photographic negative of the
reconstructed virtual image. An entirely different approach to hologram
reconstruction was used in making most of the photographs and negatives
reported subsequently. The objective of this approach was to maximize
-------
the depth of field of the reconstruction photographs. This was desired so
that photometric stv.dies could be performed on the resulting negatives.
Information on images ranging across the entire 24-foot scene was
required, hence the need for maximum depth of field in the reconstruction
photograph.
Analogous to the reconstruction photographic technique used to
obtain maximum depth of field is the old II pinhole II camera which has an
infinite depth of field but admits a very small amount of light. With a
hologram, it is possible to take advantage of the fact that each point (or
pinhole) on the hologram has lIinformationll from every point in the scene.
By putting all of the unexpanded reconstruction laser light through a small
portion of the hologram, it is possible to gain the depth of field advantage
of a pinhole camera without its disadvantage of very limited light. The
resulting reconstructed scene beam has remarkable depth of field pro-
perties and is quite bright in appearance.
Another phenomenon which must be contended with in the reconstruc-
tion process is laser II specklell or granularity. The characteristic size of
the granular pattern in the reconstructed image varies inversely with the
size of the illuminated area of the hologram. If the illuminating beam is
too small, the image may be severely compromised by the background
noise level of the granularity. Accordingly, a practical setup which was
used for photography of these holograms is shown in the sketch of Fig-
ure 19. The reconstruction helium-neon gas laser was located about 35
to 50 feet from the hologram so that the natural divergence of the beam
allowed it to expand to a diameter of 3 to 4 mm at the hologram plane.
The scene beam carrying the virtual image was brought to a focus by a
4 :inch-dia.meter lens of 26-i.nch focal length such that the range of object
dlstances m the scene occupled only about 1 inch in the real image field.
A camera lens (with normal shutter) of 210 mm focal length brought the
scene to focus again at the film plane, with the results shown in various
photographs in Section 6.
210 MM F.l.. CAMERA LENS
/ 5" DIA. X 26" F. L.lENS
~ !! ~ VHOLOGRAM
~---H---- -----I~:::;:'---Ib- - IMAGE AXIS
L 1\ ~~~ -11~o UNEXPANDED BEAM
POLAROID4x5 REAL IMAGE ~~. (3-4 MM DIA AT HOLOGRAM)
FILM HOLDER VOLUME ~
I I I I 3S~SOF ~
I-- 16"-j-42''----J- 4B"--I r ----------; He-Ne LASER
Figure 19.
Rec~nstruction camera setup for
maXlmum depth of field
-------
3.5 RECORDING FILMS AND PROCESSING
The holographic film consistently used in all phases of the program
was the Agfa 8E75 emulsion on 4- by 5 -inch glas s plates. ~:' The plates
incorporated an antihalation backing to absorb light reflected from the
othe r surface of the plate.
The development of the plates was accomplished using Eastman HRP
developer diluted 1:4 for most of the processing. Some work was done at
stronger concentrations (to 1:1). Nominal development time for the plates
was about 5 minutes at the rated dilution for the HRP developer. Each
plate was sight developed to a density range of approximately 50 percent.
After a water rinse, the plates were fixed using Eastman Kodak Rapid
Fix. After a fixing period of 4 minutes, the plates were washed (for 10 to
15 minutes) and dried.
Some preliminary recordings were made using Eastman SO-243 cut
film. Although it is possible to make holograms using this film, it is
more difficult since the emulsion is not on a stable base thus ma.king
precise reconstructions a more rigorous task. For the most part, the
SO-243 cut film used during this program was for the purpose of initial
alignment of the laser and holocamera.
Reconstruction photographs were made exclusively using Polaroid
Type 52 (positive) and Type 55 pIN (positive and negative) film in the 4-
by 5 -inch format.
*Product of Agfa-Gevaert, Antwerp, Belgium.
-------
4.
LABORATORY EXPERIMENTS
4. 1 GABOR HOLOGRAMS
Of primary concern in the application of direct imaging single-beam
holography was: (1) the resolving power of the holocamera and. the degrada-
tion of resolution as a function of distance, and (2) the attenuabon of the
reference illumination such that reconstruction would be inhibited.
Resolution was investigated using USAF 1951 Resolving Power .Test
Targets. ~:' The experimental test setup is shown in Figure 10 of Sectlon 3. 2.
Using this Gabor holocamera arrangement, two sets of resolution target
holograms were recorded, developed and subsequently reconstructed for
examination with the aid of short working distance magnifiers. The resolu-
tion target or lIobject" was placed at various measured distances away
from the holographic plate ranging from approximately 6 inches to more
than 48 feet.
The single-beam resolution target holograms were recorded in two
separate series, hologram series 10-3-69: 1-12 and series 10-8-69: 1-8.
Data from each series are tabulated in Table 1. Prior to recording the
second series of holograms (series 10-8-69), two refinements in the test
setup were made to enhance resolution. A new USAF 1951 target was
utilized since the previous example pos ses sed defects thought to be respon-
sible for a degradation in resolution. In addition, the Galilean telescope
used to expand and collimate the ruby laser illuminator was modified to
improve spatial coherence of the beam. These improvements contributed
to an overall increase in measured resolution from the second set of holo-
grams (series 10-8-69).
Data from both series of resolution chart holograms (10-3 -69 and
10-8-69) have been plotted as a function of object distance in Figure 20.
Note that a curve was generated for each of the two series of resolution
chart holograms together with a third curve which represents the com-
bined test data. For comparison, a fourth curve representing theoretical
resolution (for any optical device) Rtheo = 1. 22 \ F /D, is also shown as a
function of distance. In this equation, \ = wavelength of light, D is the
diameter of the aperture and F is the distance from the test object to the
hologram plate.
Linear and second degree curves were fitted to the data. The data
from series 10-8-69 are thought to be most representative of what can be
e:'Pected in the way of ultimate resolution over large distances using
smgle-beam holography. Note /that at a distance of 48 feet, there is an
improvement in resolution by a factor of two over the earlier measure-
ments. In summary, this is the best resolution of individual detail which
one could hope to see in the boiler volume. In reality, turbulence, tem-
perature gradients, etc.. in the boiler environment would even further
degrade resolution.
*
A description of the USAF 1951 resolution target is given in Appendix B.
-------
800
I I I I
. 10/3/69 SERIES HOLOGRAMS .
... 10/8/69 SERIES HOLOGRAMS
I
SECOND DEGREE CURVE 17
FIT, 10/3/69 SERIES ......... ,,4
/
/
/
/ ~
, 1/
.
SECOND DEGREE CURVE /' J
FIT, 10/8/69 AND
10/3/69 SERIES """""""",J V
I
/ ~ V
I..
/4 V _.-' ~
-' 7 ./
) ./
/- / ~ ~.
,,/ / l/ '" ........ r--... LI NEAR FIT,
/ ~ :./' 10/8/69 SERIES-
... ONLY
~ ~
.. ~ V
~
,/ ~ ...,.. 1.22>'
- = RTHEO...
~ V D/F ~.
~.; -L..
..-
~~ c-..... . .... -
. .... j88I
7 -. ..-
. -.. .-
1200
1100
1000
900
VI
Z
o
~
u
~ 700
Z
z
Q
5 600
-'
o
VI
w
~
500
400
300
200
100
o
o
5
10
15 20 25 30 35 40
RESOLUTION CHART TO HOLOGRAM DISTANCE IN FEET
45
50
Figure 20.
Single-beam holocamera resolution measurements
-------
Table 1. Hologram Resolution Measurements - Gabor Technique
USAF 1951 Resolution Target
.
Series and Object (target) Best Reading Equivelant Particle Remarks
Hologram No. Distance Lines (mm) Size (microns)
10-3-69: 0 0'-67/8" 55. 0 9
1 6'-0" 10.0 50 'Laser not Q- switched
2 6'-0" 10.0 50 Laser not Q- switched
3 6'-0" 7.0 70
4 12'-0" 6.0 83
5 18'-0" 2,0 250
6 24'-0" 2.0 250
7 30'-0" 0.4 1250 This point omitted in curve fit
8 36'-0" 1.0 500
9 42'-0" 0.7 715
10 48'-0" 0.44 1130
11 53'-1'0" 0.4 1250
10-8-69: 1 6'-0" 9.0 56
2 12'-0" 5.0 100
3 18"-0" 2.0 250 Low contrast negative
4 24'-0" Thin negative, no reading
5 30'-0" 1.6 312
6 36'-0" 1.6 312
7 .42'-0" 1.0 500 Many confusing images
8 48'-0" 0.9 555 Many confusing images
In addition to the resolution tar~,et holograms, three sets of holo-
grams of glass beads were recorded ',' Two of these latter three sets of
holograms used glass beads of 40 to 50 mesh and the third used beads of
120 to 170 mesh size. Size data for various mesh numbers are shown in
the Table 2.
Table 2.
U. S. Standard Sieve Series, 1940*
Mesh
No.
Size
(microns)
Sieve Opening
(inche s )
40
50
70
120
170
200
230
325
420
297
210
125
88
74
62
44
.0165
.0117
. 0083
. 0049
.0035
.0029
. 0024
. 0017
"-
'''Ref. :
C. D. Hodgman, ed, Handbook of Chemistry and Physics,
43rd Edition, The Chemical Rubber Publishing Co.,
Cleveland, Ohio, 1961. p. 3401
*
No. 831 titanium. glas s beads (high index of refraction) purchased from
the Bavin Co., 2500 W. 6th Street, Los Angeles, California.
-------
The procedure for recording holograms of glass beads was similar
to that described for the resolution chart experiments. A fine stream of
beads was dropped through the holocamera scene volume during the laser
pulse. Recordlngs of the beads were made at 6-foot intervals along the
optical path. The purpose of these tests was to record holograms of a
scene similar to that which appears in the Unit 10 boiler superheater
region. Reconstructions of these holograms were subsequently used to
determine if one could focus on small distributed objects and determine
where in the scene volume these objects were located. Resolution of known
particle sizes at various object distances could also be compared with the
earlier resolution target measurements.
In the first set of holograms of 40-50 mesh glass beads, well defined
images (297 to 420-micron-diameter beads) could be observed at an object
distance of 6 feet. In the reconstruction of the holograms recorded at
object distances of 12 and 18 feet, respectively, bead images were visible
but les s well defined (i. e., the edges of the images were fuzzy). The holo-
grams of beads located at distances greater than 18 feet exhibited even
poorer reconstruction images. The results compared approximately with
the resolution chart measurements (Figure 20) in that 300 to 400-micron
particles are distinguishable at distances of 25 to 35 feet. At greater
distances, the reconstructions appear only as blotches. Similar results
were observed with the holograms sets of 120-170 mesh beads.
One of the glass bead Gabor holograms was selected for data reduc-
tion. The photograph of Figure 21 shows a helium-neon gas laser recon-
struction of a dispersion of 40-50 mesh (297- to 420-micron diameter)
beads located at a distance of 6 feet from the hologram plate. Bead images
on three 1-inch- square areas of the film were measured. The resulting
data were grouped into 25-micron intervals and counted. A computer
program was used to calculate the cumulative volume fraction, 1: ND3 /
(1:ND3) total where N is the number of beads for each 25-micron interval
and D is the median diameter of the corresponding interval. A plot of
these data is shown in Figure 22. Note that about 25 percent of the beads
fall outside of the manufacturers nominal size range (297 to 420 microns)
on both ends of the distribution.
The reconstructed scene in a Gabor hologram produces a negative
image. This is seen in reconstruction photographs of glass bead holo-
grams. In the real image produced by the holograms, the shadows of the
beads show as bright spots against a dark background (Figure 21). Note
also from this reconstruction photograph that the background is not
uniformly dark, but is generally mottled and contains another set of less
luminous spots. A similar effect is seen in the real image resolution
target reconstruction photograph of Figure 23. In this figure, the spurious
images look like three-bar chart elements out of place.
A real image of glass beads at a distance of 12 feet from the holo-
gram is shown in Figure 24. This photo was made from hologram No.2
of 7 October 1969. In a separate series of glass bead holograms made on
9 October the number of beads within the scene volume was greatly
reduced t~ avoid cross -modulation between images. Figures 25 and 26
are from holograms No.1 and No.2 of that series taken with the beads
at 6 and 12 feet from the plate. Images of four beads are evident in
-------
(~ ~' ",'.'''" " C, .. 1)f ".. ,'8' ',':t'- . ,y,'" ~ .....
...'iii '. ~p "1r' ~....,",. , " "~'
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",: '"' ~' . .,.:n!:, .L ,:~:,,~'. ;~,,, r,~' 'J<~ ',J), \
.,"'" , ,..~ ' --~ . ~ ,...", ~ ~ ;If
ex' '.;'", ,.' " {" ~, ',...... ~ ' ~
...(/t,r-"'~~' " "f~.., ,iJ6A, !41,~ ~ .., ,,~., .::'#lI.~,.'," -.;,. ;:'.
- '~ ':!IIIJIIIII'J'J ~~j", l~f.A ¥i-" ..
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-- '.0 ,,--- ,'", "*, ' '. ' '. ..' ;tit....
. '" 4- ' ;"./. ~ . , ~.. ,..<' ,"" ,.,", ;' '1'.
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, ,'. . ';'~" ... . ~ ~. ~ '. ..,. , ',"4; ,
.It' .".~it.f ~; ,',.. f 4-. .JI!.""'''' " . '~1 \~ '''';:';, t , ,
~ .". > ?...,"« '.~ - - J" . . ~. .'. ,~ft
Figure 21.
Helium-neon laser reconstruction of a pulsed ruby
hologram. Reconstruction photo shows a distribution
of 297 - to 420-micron-diameter glass beads located
a distance of 6 feet from the hologram plate. Beads
are magnified by a factor of 5. 9.
1.0
o
o
100
.8
--I
«
I-
o .6
I-
M---
o
z
t!
M'
o
Z
N
.4
.2
Figure 22.
200 300 400 500
BEAD DIAMETER, D IN MICRONS, .
Cumulative volume fraction versl1:S..-bead:diameter.
Distribution measured from bead'~_ge$ seen in
Figure 1 9 ' ;,'
600
-------
Figure 23.
Real image from hologram No.1, series 10-8-69.
Image comes to focus at 6 feet from the hologram
..
..
I. ,"
"
" .. ... ,. I. *" - ¥' J- #
'" . ,. ~l .~. '. -"";f' .,
, ,,-,. ~ . .....
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-. 1-"." -;;.. 1}.,-.-
-(0 '" ' .:..,:~.,p., ,,~, ~ ..~'
-.to> .... 'T"'P"';
." .. ~ .. . , ,
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- .f ' -.:; .
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.." ~.~i ,.,:.. -.,4
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'. ... . ~p , .. ~ ' ~ -.~ ..- ' , ",.
, ,;0', - ~"'- ", .." II'.' -'-I. ,.. ..
.. '''1'4# ~.' ~ - '" "..' .
- ",".. ',' .j'~,:; , . f~. ./'J~~'":
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~~,..J .,. «) .. ,- ."
.~~ .t- ~'#, 1i.. .~.t ~l';' ~::,~-,,":.i f..t
;'" . w -' . . ;
-------
Figure 25.
Reconstruction photo of stream of 40-50 mesh
glass beads at 6 feet from hologram. Four bead"
im.ages are visible. Num.ber of objects in scene
was reduced to reduce the num.ber of spurious
images.
Figure 26.
Reconstruction of images of 40-50 mesh glass beads
at 12 feet from hologram. Five bead images are
visible.
-------
Figur.e ~5 and five beads in Figure 26. In both instances, image sharp-
ness 1S lmproved as the result of using fewer objects in the scene.
The reconstruction photographs and data reduction presented here
have all centered on the holograms made using the more coarse (40-50
mesh) glass. beads in the holocamera scene volume. No really satisfactory
reconstructlon photographs of hologram recordings of the smaller mesh
size beads were made. In viewing the reconstructions of beads in the
120 to 170 mesh size range (nominally 125 to 88 micron diameter particles)
individual bead images became indistinct at 18 feet and beyond.
4. 2 TWO-BEAM SCATTERED LIGHT HOLOGRAMS
For the application at hand, that of identifying, locating and measur-
ing the boundaries of large ensembles or clouds of limestone particles
across a 24-foot combustion volume, the technique of single-beam holo-
graphy proved inadequate. Since the reference and scene beams of a
Gabor hologram are coaxial, the reconstructions tend to be somewhat
"noisy" and contain spurious images. Identification and location of objects
in a complex scene becomes more difficult. A further handicap is the
inherent degradation of size resolution with increasing distance. In the
absence of a finite object on which to focus, it becomes impossible to
achieve any spatial resolution. In the limit, the presence of very large
ensembles of particles encodes the reference illumination of the single-
beam hologram resulting in an inability to reconstruct a meaningful holo-
gram scene. Such was the condition in the boiler at the Shawnee Power
Plant.
Because of the inherent limitations of single-beam holography, an
alternate approach was selected for evaluation. Under sponsorship of an
independent research program at TRW, a method of recording low angle
forward scattered light was tested. The concept of scattered light holo-
graphy of clouds of particles had been conceived previously at TRW when
it was realized that Gabor holography would not be adequate. Reduction
to practice was accomplished concurrently with the Phase I effort of this
program.
Basically, the scattered light holography technique is a modification
of a more conventional TRW two-beam transmission holocamera system.
The initial holocamera setup, used to demonstrate feasibility in a labora-
tory configuration, was described in Section 3. 3. A series of test scenes
was recorded with the two-beam scattered light holocamera setup. These
include tufts of cotton, glass wool fibers and dust from chalkboard erasers.
The objects were placed at specific distances into the scene volume along
the laser scene beam path. The depth of field for the holocamera was
approximately 50 feet in length.
Reconstruction of the recorded holograms was accomplished using
a continuous wave gas laser. The laser beam was expanded and collimated
to approximate that of the original reference beam. The virtual image of
each reconstructed scene was observed by looking through the hologram
plate as through a window. Since the reference beam arrived at the holo-
gram plate with an angular displacement relative to the scene be~m, the
reconstructed virtual image of the scene was made to appear aga1nst a
-------
uniformly dark background free from extraneous images. Upon viewing a;
typical reconstruction, the observer sees a bright point of light at a great'
distance into the scene (in reality, the laser light from the last corner
prism some 50 feet away from the holographic plate), light scattered from
various objects placed in the scene at corresponding distances (cotton, .
glass fibers, etc.), and innumerable bright points of light along the laser
scene beam caused by low angle scattering from airborne dust particles.
Figure 27 is a typical reconstruction photograph made from a holo-
gram (10-31-69:1) recorded during the scattered light tests. The photo-
graph shows back lighted cotton tufts located at 6 and 12 feet from the
holographic plate. The photo was made with a camera lens stopped to
f/32 for maximum depth of field to simulate the view obtained with an
observer's unaided eyesight. (In direct viewing, an individual's eyes
compensate for angles and focus so unconsciously that everything in the
scene seems in focus at once; with a camera, this is not so.)
Figure 27.
View of the virtual image of low-angle forward scattered light
from c?tton balls at 6 and 12 feet from the hologram.. Light
from alrborne dust particles traces illuminating beam back
to laser 50 feet away.
The image ~f this same hologram (10-31-69:1) was examined with
~ small astronomlcal telescope, and it was found that a great many objects
ln the scene could be brought into separate sharp focus W.th thO . t
m t th f I d' . 1 1S lns ru-
en e oca ls.tance from 6 feet to infinity maps into about a 6-inch
trav~l of th~ eyep1ece focus adjustment so that a scale of distances is
readlly avallable for location of object distances in such a s An.
e:am.ple of how s~ch discr~min.ation is made using the focus c:;;~stment of
t e vIew ~amera IS shown ln Flgure 28 which is a composite of three views
~t. focda~ dIstances of 6, 12, and 35 feet beyond the hologram Plane and
tr1S a Justment of f/8. '
-------
Figure 28.
Composite views of a scattered light reconstruction
at focal distances of 6, 12 and 35 feet
-------
5.
SHAWNEE UNIT 10 EXPERIMENTS
5.1 GABOR HOLOGRAMS-UNIT 10 SUPERHEATER
Gabor holographic recordings of fly-ash particles in the Unit 10 super-
heater (elevation 392 feet) were attempted during Dece~ber 196?, .usi?g the
holocamera apparatus described in Section 3.2. The hmestone InJect~on
system was not operating during this initial holography work at the boller.
Twenty-four holographic recordings. were made of part.i~ulate in the
superheater region. These are tabul~ted In Table 3. ~ addItIon to the
initial six alignment tests, 23 more sIngle-beam recordIngs were made
using both Agfa 8E75 plate and Eastman SO-243 cut fihn. Laser light atten-
uation across the 47 -foot optical path of the Unit 10 sUJ:Serheater (see Fig-
ure 11) proved more severe than originally estimated. There was insuffi-
cient ruby light to expose the Agfa 8E75 emulsion. All efforts to obtain an
exposure with Agfa 8E75 plate failed. The Eastman SO-243 emulsion, which
has a sensitivity 100 times greater than the Agfa plate, could be adequately
exposed such that 5 to 8 minutes development time in HRP developer (diluted
4:1) produced a negative of reasonable density and contrast.
Although exposures on SO-243 cut fihn sheets could be made, the
results were not satisfactory. Upon reconstruction, no meaningful infor-
mation could be abstracted from the hologram. In only a few instances,
apparent real images could be brought to focus at various distances into the
reconstruction field (for example, in holograms 1253 and 1254). The images
appeared to be approximately 1000 microns in size. Examination of the
holograms, however, failed to reveal any obvious corresponding fresnel
diffraction patterns for these few images.
5.2 SCATTERED LIGHT HOLOGRAMS-UNIT 10 BOILER
Phase III scattered light holography tests at the Unit 10 boiler (eleva-
tion 365 feet) were divided into several series of experiments using the
two-beam holographic test setup described in Section 3.3 and shown in the
schematic diagram of Figure 15. The setup of the holocamera and the con-
duct of the test program required a total of 3 weeks during the month of
February 1970.
A total of 79 holograms was recorded under a variety of operating
conditions during the 3 -week feasibility test program. >:' Figure 29 is a
matrix of the various boiler and holocamera operating conditions. Test
c~nditio~s ~re indicated around the periphery of the matrix diagram.
LIsted Wlthm each segment of the matrix are the record numbers of the
specific holograms used for analysis and data reduction for the indicated
test conditions.
-',
"'Appendix C presents basic holographic and boiler operating data and
information on each of the 79 holograms. These holograms are cur-
rently on file at TR W Systems.
-------
Date
12-4-69
12-8-69
W
..0
12-9-59
Hologram
Number
(1)
(2)
(3)
(4)
(5)
(6)
1232
1233
1234
1235
1237
1238
1239
1240
1241
1242
1243
1244
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
Film
Faulsion
S0-243
"
"
"
"
"
8E75
..
"
"
S0-243
"
..
"
"
..
"
"
"
8E75
"
"
Table 3.
IIRP
Dilution
4:1
4:1
4:1
4:1
4:1
4:1
4:1
4:1
4:1
2:1
2:1
2:1
2:1
2:1
2:1
2:1
4:1
4:1
4:1
4:1
4:1
4:1
4:1
1:1
1:1
1:1
Phase II Holograms - Unit 10 Superheater
DeveloDment Laser Pulse
Time Kin. TeDiD. of Diode Outout
4
2
2
2
3
4
8
9
8
8
2
2.5
2.5
3
3
3.5
2
4
8
6
5
5
5
9
4
8
65
68
68
69
70
70
64
66
66
67
0.16 volt
0.21
0.25
0.29
0.24
0.25
0.20
0.20
0.21
0.19
0.15
0.17
0.20
0.26
0.22
0.17
0.19
0.21
0.34
69
69
63
64
66
67
67
67
69
65
65
68
0.22
0.34
0.33
Remarks
Alignment check. Unexpanded beam, no Q-switch. Film saturated.
Repeat of 12-4-69 - No.1
Alignment check with 4 in.dia.
Exposure non-uniform.
collimated beam. No Q-switch.
Same as 12-4-69 - No.3. Image contrast "soft."
Same as 12-4-69 - No.3. More contrast, exposure non-uniform.
Same as 12-4-69 - No.3. Good contrast, exposure non-uniform.
Dye cell Q-switch, 4 in.beam. Laser double pulsed. Plate fogged
~ood laser pulse. No image. Plate accidentally fogged.
110 iaage.
110 image.
!sual beam alignment check. No film in camera.
epeat of No. 1237.
Very weak image, underdeveloped.
~eak image, underdeveloped.
~eak image, underdeveloped.
Underdeveloped.
Underdeveloped.
~eak image, underdeveloped.
~eak image.
~oderate contrast.
[;ood contrast.
[;ood. Will reconstruct but with little apparen~
~ood contrast, but little apparent information.
~ame as No. 1254.
information.
lear. No image on plate.
Laser accidentally pulsed early
~o image.
~o image.
~o image.
-------
No Limestone Limestone
No. 1391 No. 1544 Rear
No's. 1547 Port
No. 1327(1) No. 1535 thru 1549
Power @ No. 1331 ( ) No. 1491
140 MW No. 1381 2 No's. 1 568 No's. 1562
No. 1534 thru 1573 thru 1567
Front
Port
Power @ No. 1505 No. 1506
85 MW
Rear
Port
Co 11. Beam Fan Beam Co 11. Beam
Notes: (1) Reconstruction photograph to obtain scene beam "fingerprint" only.
(2) USAF 1951 target in scene. Reconstruction photos used to show
extreme depth of field available
Figure 29.
Matrix of Shawnee Unit 10 holographic tests and holo-
gram numbers analyzed for information and limestone
plume data
5.2.1 Operating and Test Conditions
With respect to the holocamera, two variables existed; namely, the
use of a collimated scene beam or a flat "fa;n-shapped" scene beam. When
a collimated scene beam was employed, an essentially cylindrical shaft of
ruby light passed through the boiler. Some scene beam divergence did
occur. The beam, initially about 1 inch in diameter at prism No.4 (enter-
ing the boiler), was about 2 inches in diameter upon reaching the holographic
film plate. The "fanned" ruby light scene beam was produced by placing
a -2 diopter cylindrical lens ahead of prism No.4 (Figure 15). This re-
sulted in an essentially flat horizontally diverging scene beam in the form
of a triangle normal to the boiler combustion gas flow. The fanned scene
beam permitted somewhat more coverage of the phenomena occurring within
the boiler. The two diffe.rent scene beam geometries are shown in the sche-
matic diagrams of Figure 30.
Of primary interest to the test program was the ability to discern and
locate those portions of the limestone cloud passing through the scene beam
of the holocamera. In this respect, holograms were recorded in the pre-
sence of limestone injected from the front (south) and from the rear (north)
side of the boiler. Limestone injected from the front side of the boiler was
accomplished using a row of injection ports at elevation 359 feet, 9 inches.
The nearest injection port to the scene beam was approximately 3 feet,
7 inches west; and 5 feet below the scene beam inlet port at elevation 364
feet, 9 inches. On the rear or north side of the boiler, the nearest lime-
stone injection port was in line with the scene beam exit port and 16 feet
below it at elevation 348 feet.
-------
t
t ,..,,1 inch
,.." 2 inches J
t .61.- North Wall
Elev. 365
A.
Collimated Scene Beam
I~
t
t ,..,,1 inch
B.
Fanned Scene Beam
.[
t
241-0"
(Boiler Tube ~IS)
~
~
,.." 18 i nches ~
""*'- North Wall
Elev. 365
-
Figure 30.
Schematic diagram of ho1ocamera scene beam
geometries used to record particulate in the
Unit 10 boiler
During the holography test series, limestone injection rates through
the front four ports (on 3-12-70) varied from approximately 7500 to 11,000
1b/hr or about 1870 to 2750 1b/hr through each port. Twelve holograms
recorded while limestone was being injected through these front ports. All
of these recordings were evaluated and reduced for limestone plume
information.
Holography tests with limestone injected through the six lower rear
side injection ports were conduction on 3-6-70 and on 3-12-70. Injection
rates for the 3-6-70 series varied between 6000 and 7000 1b/hr or about
1000 to 1165 lb/hr per rear injection port (elevation 348 feet). During the
latter series (3 -12-70), injection rates ranged from approximately 3000
to 8000 lb/hr or 500 to 1330 lb/hr through each port. In all, 31 holograms
were recorded of limestone injected through the rear set of injection ports.
Of these, six were used for data acquisition.
In summary, 18 holograms, covering limestone plumes injected from
both the front and rear side injection ports were evaluated.
The remaining operating variable was the power output of the boiler.
This is a function of the pulverized coal and air feed rates. Hence, the
particulate in the boiler (fly-ash) might be expected to vary approximately
as the power outputs of the boiler. A series of holograms was recorded
during a boiler power excursion on 3-11-70. The boiler was operated at
power levels ranging from approximately 85 to 140 mw. Holograms from
this series were qualitatively evaluated; however, no quantitative data were
obtained.
-------
5.2.2 Data Reduction from Holographic Reconstructions
The utility. of the holographic method of detecting limestone .p~UIIles
in an operating steam boiler is a function of the measurable quantltles
which may be obtained from the reconstructed images. Wit.h two-beam
scattered light holograms, the quantities measured to date Include:
.
Axial distances between hologram and focusable images
.
Angular distances between images
.
Luminous intensity variations.
Axial distances between the hologram plate and images in the recon-
structed scene have been measured with the ranging telescope. The
method is described in Section 3.4 of this report. If the geometry of the
boiler and holocamera arrangement are known, location of limestone
clouds relative to the boiler walls can be determined.
Measurement of angular distances within the virtual image field
using the wide depth-of-field reconstruction photographs has also been
accomplished as part of the hologram data reduction process. From these
measurements and the known geometry of the scene beam and boiler port-
ing at elevation 365, a check on telescopic measurements of axial distances
is possible. Good agreement between the results of the two methods was
obtained.
Direct measurements of luminous intensity in the reconstructed holo-
graphic images were not accomplished. However, microdensitometer
traces on photographic negatives of the reconstructions have been made and
proved extremely useful. To date, the densitometer measurements of
changes in negative intensity (relating to the presence or absence of clouds)
have yielded only relative values since a suitable calibration or reference
illumination on the original hologram is lacking. Qualitative comparisons
have been made between negatives taken from similar holograms, for
cases with and without limestone injection. Generally, the limestone
traces show luminous intensity variations, often not discernible to the
unaided eye, which reveal the presence of limestone clouds. In those
instances where visible clouds are obviously present, the microdensitometer
traces confirm the pronounced variations observed in the hologram recon-
struction and measured with the ranging telescope.
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6.
RESULTS AND DISCUSSION
Although a significant amount of work was devoted to the technique
of single-beam or Gabor holography, the only substantive results for in
situ boiler studies were obtained with the two-beam holography technique
of recording low-angle forward-scattered light. This section describes
the scattered light holography results obtained during the 3 -week period
of Phase III at the Shawnee Unit 10 boiler.
Of the original 79 scattered light holograms made during Phase III,
25 were eventually selected as representative of the eight test condition
categories listed in the test matrix of Figure 29 in Section 5. 2. 1. * Since
the basic purpose of the holographic test program was to demonstrate a
capability to record the presence of limestone plumes or clouds, 18 of the
25 holograms selected were recordings made during limestone injection
tests. Much of the subsequent discussion centers on these latter 18 holo-
grams.
6.1 TESTS WITHOUT LIMESTONE INJECTION - 140 MW
Initial tests at Unit 10 were concerned with demonstrating the holo-
graphic technique and refining the test setup alignment. Holograms were
made with a collimated scene beam and later, with a fan-shaped scene
beam. Nominal boiler power output was 140 mw.
Holograms No. 1327 and 1331 are representative of these early tests
(see Appendix C). Hologram 1327 was made with the scene beam light
directly incident on the film plate. In addition to confirming alignment,
it gave a direct measure of the scene beam divergence across the 24-foot
scene volume. Figure 31 is a contact print made from this hologram.
Figure 31.
Collimated scene beam" fingerprint" on holo-
graphic plate after traversing 24-foot com-
bustion volume of Unit 10 boiler
*
See Appendix C for a complete listing of the 79 Phase II holograms.
-------
Hologram 1331 was the first recording of scattered scene light.
made on the Agfa 8E75 emulsion. It provided an excellent reconstruchon
and exhibited numerous apparent discontinuities along the laser beam
axis. These could be seen by viewing the reconstructed.holo~ram's .
virtual image from varying positions and noting the nonhnearlty or shIm-
mering of the beam axis. These irregularities were termed "therm~ls"
and were originally thought to be caused by strong temperature gradIents
and turbulence within the combustion gases. It was later found, however,
that these so-called thermals were induced into the scene by a draft of
cold air entering the boiler through the open viewing port at the recording
station (Figure 17) of the holocamera setup. * A red glass filter (Corning
CS-2-57) was subsequently used as a "window" to cover the open view
-port while recordings were being made. This technique eliminated the
appearance of thermals in the reconstructed holograms.
Holograms 1331 and 1534 were reconstructed and (the virtual image)
photographed. Single scan microdensitometer measurements were made
with reconstruction negatives obtained from each hologram. An example
densitometer scan is shown in Figure 32 for hologram 1331. Also shown
is a reconstruction photograph of the laser scene beam which corresponds
to the negative used in the densitometer measurements. The insert photo-
graph is oriented in the direction of the scan trace. The observer is look-
ing across a light beam spanning 24 feet with the near or north boiler wall
at the right edge of the photographic image.
Densitometer measurements of hologram reconstruction photographs
of fly ash (only) were characterized by a relatively straight line slope to
the resulting traces. This may be seen in the illustration of Figure 32.
Also, the intensity of the light scatter appeared uniform based on the nomi-
nal band width of the trace oscillations. These characteristics would imply
that relatively uniform fly ash distribution acros s the boiler generally
existed.
In another test (hologram 1381) during the first series, a USAF 1951
resolution target was placed before the open boiler port, a distance of
28.5 inches from the holographic film plate. Reconstruction photographs
we.re made by f?cusing a view camera first on the virtual image of the reso-
luhon target (Flgure 33a) and next on the scattered light from the scene
beam (Figure 33b). In the upper photograph, the three-bar pattern of the
resolution target located 2 feet, 4 inches from the holographic plate is in
sharp focus while the scene beam scattered light is blurred in the back-
ground. The lower photo shows light scattered around the area of the
i-inch No.4 prism (lower portion of the light image) some 33 feet, 3 inches
from the hologram. .In this illustration, the bar pattern of the resolution
target is more grossly out of focus in the foreground.
.The remaining two holograms in the tests at full boiler power output
and wIthout limestone injection represent demonstration of the technique
using a .collimated and then a fanned beam (holograms 1534 and 1491,
respectIvely). These holograms, when reconstructed, exhibit a general
characteristic of uniformity and brightness acros s the 24-foot scene length.
*
A negative pres sure gradient exists while the boiler is operating (1-2 inches
of water) thus drawing ambient air into the open port.
-------
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-------
Figure 33a.
Reconstruction photo of hologram 1381.
Copy camera was focused on resolution
target 28 inches from holographic plate.
Figure 33b.
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the prism approximately 33 feet from the hologram
plate (hologram No. 1381). The out-of-focus reso-
lution target is barely discernible in the foreground
of the scene.
-------
It was concluded from this first series of tests that two-beam
holography of scattered light in an operating boiler is entirely feasible.
Each of the recordings possessed excellent three -dimensional qualities
even though viewing was limited by use of a 4-inch inside diameter by
18 -inch long boiler port on the observing or camera side of the test setup
(see Figure 17). This had the effect of restricting one to viewing the
large boiler combustion scene through a "knot hole. II Holograms recorded
in the initial series also served as a basis of comparison for subsequent
tests with limestone present in the boiler.
6. 2 TESTS WITHOUT LIMESTONE INJECTION - 85 MW
A serie s of holograms was recorded at various power levels of boiler
operation. These were mad.e during a power excursion with Unit 10 on
3-11-70 and are described in Lines 32 through 47 of Appendix C. It was
thought that such a series of holograms would illustrate the sensitivity of
the holography technique to changes in general particulate concentrations
since at lower power settings, one would expect a corresponding reduction
in fly ash.
No systematic data reduction was attempted of the power excursion
series holograms. Rather, emphasis was placed on reducing holograms
recorded in the presence of limestone. Holograms 1505 and 1506, however,
are excellent examples of recordings made at low power (92 and 85 mw,
respectively). The first hologram, No. 1505, was recorded using a colli-
mated beam. The companion recording was made with a fanned scene
beam. Both produced bright reconstructions and indicated that a very uni-
form scattering of the scene light occurred acros s the 24-foot width of the
boiler. This in turn suggests a uniform distribution of fly ash.
The brightness of holograms 1505 and 1506 would further indicate
that attenuation of the scene light was significantly reduced. This was
physically confirmed by visually observing the combustion flame and
opposite boiler wall during the power excursion tests. At the low power
ratings, four of the 16 pulverized coal injectors were shut down and the
flame was visibly more transparent to the red light from the continuous
helium-neon (X. = . 6328f.1) gas laser and the pulsed ruby illuminator.
Turbulence was also reduced since gas laser beam flicker was almost
nonexistent. Finally, the tube wall on the opposite side of the boiler was
clearly visible at the lower power levels. This was in marked contrast
to visual observations made at nominal power levels of 140 mw where the
helium-neon sighting laser was barely visible and exhibited a considerable
amount of flickering.
The holograms recorded during the power excursion could have been
better. It was discovered that the reference beam was not perfectly aligned
onto the hologram during part of the test series. This resulted in several
weak reconstructions. Of significance, however, was the increase in laser
light transmis sion which was visually observed at the low power setting of
the boiler. This implies a substantial reduction in the number of particles
per unit volume.
-------
6. 3 TESTS WITH LIMESTONE INJECTION - 140 MW
Eighteen h~lograms were selecte~ f~r dat~ reductio~ and evaluation
in the test series where limestone was Injected Into the bOIler. These are
listed in Table 4 which is a compilation of data on boiler operation, the
limestone injection system and limestone plume images recorded by ~he
respective holograms. The hologram numbers co~r?sp~nd to those gl~en
in the test matrix of Figure 29, for the limestone InJechon tests (Sechon
5. 2).
The first six holograms of Table 4 were recordings of portions of the
limestone plumes or clouds produced by injecting through port No. 7A on
the rear (north) side of the boiler at elevation 348 feet. The remaining 12
holograms (comprised of collimated and fanned beam recordings) are of
limestone plume images from clouds formed by injecting through the front
No.2 port.
Evaluation of plume information in the various limestone holograms
was made by: (1) visual observation of the reconstructed virtual images;
(2) measurements of cloud images with a ranging telescope; and, (3) densi-
tometer measurements of reconstruction photographic negatives. In the
latter method, collimated beam hologram reconstruction negatives received
a single scan with the densitometer instrument. Selected fanned beam
reconstructions were "mapped" by making repeated adjacent scans until the
entire image area was covered.
Reference to Table 4 shows that 28 percent of the holograms evalu-
ated exhibited voids in the cloud structures. The voids could be measured
and counted. The smallest void noted was approximately 3 inches (No. 1544),
and the largest (No. 1571) was about 5 feet in width. In one example, holo-
gram 1573, a void or striation in the horizontal plane (normal to the combus-
tion gas flow) was observed. In effect, two parallel clouds existed which'
partially overlapped in the middle of the boiler.
The widest cloud noted (without voids) was approximately 19. 5 feet
and was seen in hologram 1562. The narrowest was about 4 feet (hologram
1573). Analysis of the cloud measurements for both front and rear injected
limestone plumes showed that the average cloud width for each group was
about 9. 5 feet. This suggests that strong streamline flow conditions may
exist in the boiler and that lateral mixing or dispersion of the clouds is
limited with changing elevation. That is, once segments of the plume
geometry are formed (upon injection) and some initial expansion is com-
pleted, the segments ascent through the boiler in stream tubes.
A factor which tends to reinforce this contention is the relative sta-
bility and similarity of the limestone plume centerline locations with regard
to the side of the boiler from which the limestone was injected. For the
six plumes recorded with limestone injected from the north side of the
boiler, the mean centerline location was approximately 9. 6 feet from the
wall. Similarly, the mean centerline location for the 12 recorded clouds
formed by injecting limestone through ports on the south side of the boiler
-------
oj:>.
...0
Table 4.
Summary of data obtained from hologram recorded
in the presence of injected limestone
Boiler Data Limestone Injection Data L imestooe Plume Data aod Descriotion
Air Flow Rate S02 Conc. COrrll1ents
Ho \ ogram Time Power M Lb/Hr(l) Port Port Elev. Port Lb/Hr(2) Air Meter %(3) PI urne Location PI ume Wi dth No. of Width of
No. Date Hrs. MW No. Ft. Location Reading-% From S. Wall-Ft. in Ft. Voids Voids-Ft.
1391 3-6-70 1422 14.1 950 7A 348 Rear 1170 28 Unknown 3.0 to 17.0 14.0 0 --- Telescope measurements only.
Uniform cloud with indistioct edoes.
1535 3-12-70 0847 140 1000 7A Rear 500 30 1 g.O 12.0 to 20.0 8.0 0 --- Tele. meas. ooly. 8ri ght spots (slao?) at 4.0 ft.
1544 0920 141 1000 7A Rear 1080 30 23.6 14.5 to 23.5 9.0 2 1.0/0.25 20-25% increase in scattered light intensity
in plume regions.
1547 0925 141 1000 7A Rear 1170 30 23.6 6.0 to 22.5 16.5 1 2.0 One bright cloud near far wall gradually dissipat-
ing to North wall. Maximum intensity increase 200%.
1548 0928 141 1000 7A Rear 1080 30 23.5 10.0 to 19.5 9.5 0 n- Prominent cloud without apparent voids.
1549 0931 141 1000 7A Rear 1000 30 23.4 8.0 to 17.0 9.0 0 _n Major cloud - 80% increase in intensity.
22.7 to 23.8 1.1 0 _n Secondary or minor concentration with -15%
increase in intensity.
1562 1108 141 990 2 360 Front 2750 25 23.4 4.0 to 23.5 19.5 0 --- Apparent uniform intensity over -19-20 ft of boiler.
Presence of limestone questionable.
1563 1110 140 990 2 Front 1870 25 22.7 7.0 to 16.0 9.0 0 _n Maximum increase in intensity is -60%. One cloud
and no apparent voids.
1564 1113 140 990 2 Front 1870 25 22.5 1.5 to 17.5 16.0 0 n- Major cloud, 100% increase in intensity. Possible
minor cloud (+10%) in 21-23 foot region.
1565 1115 140 990 2 Front 1870 25 22.2 4.0 to 7.0 3.0 1 -3.0 Low intensity, small cloud on far side.
10.0 to 23.0 13.0 0 n- Major nearly uniform cloud over most of boiler with
50% intensity increase over background noise.
1566 1117 140 990 2 Front 1870 25 24.0 3.0 to 10.0 7.0 0 --- Tele. meas. only. Dark area casting shadow at
approximately 10 ft. mark.
1567 1120 140 990 2 Front 1870 25 23.4 0.5 to 11.0 9.5 0 --- Major cloud with intensity increase of -500%.
1568 1122 140 990 2 Front 2750 25 22.9 3.0 to 8.0 5.0 0 n- Tele. meas. only. Possible lateral structure
in cloud (far beam).
1569 1124 140 990 2 Front 2750 25 24.5 2.0 to 9.0 7.0 0 -n Tele. meas. only. Lateral structure with possible
void areas.
1570 1125 140 990 2 Front 2750 25 24.5 2.0 to 13.0 11.0 0 _n Tele. ..eas. only. Some lateral cloud structure not!!d.
1571 1127 140 990 2 Front 2750 25 24.0 0.5 to 13.0 12.5 1 -5.0 Telescope measurements verifi!!d with densitometer trace.
1572 1129 140 990 2 Front 2750 25 23.2 3.0 to 11.0 8.0 1 '1.0 Tele. ...... only. Small pocket or void at 5 ft. plus
latera 1 structure.
1573 1130 140 990 2 Front 2750 25 23.6 2.5 to 11.0 8.5 0 _n Tele. meas. only. Striation in horizontal plane
(Down) formin9 2 parallel clouds.
10.0 to 14.0 4.0 0 -n
(Up)
NOTES:
(l) Approximate a..rage values taken from Unit 10 Loa Sheets for 3-6-70 and 3-12-70.
(2) Average limestone Injection flow rate per hour per Injection port.
(3) S02 concentration in percent of 4000 ppm. Data obtain!!d from O. T. Clay, NAPCA, and was obtain!!d from the "8"
-------
was about 7.5 feet from the (near) wall. * The 2-foot variation in center-
line distance from the near wall for both injection locations m~y we~l be
accounted for in'the relative difference of injection port elevabon wlth
respect to the probing laser beam. In other words, those clouds de~ected
near the north wall (rear injection ports) were more fully expanded mto
the flow field. Also of interest is the fact that the minimum and maximum
centerline distances from the reference boiler wall were approximately 5
and 14 feet, respectively. for plumes injected from both the north and the
south injection ports.
Densitometer measurements of reconstruction photographs (negatives)
of limestone clouds were made of both collimated and fan- shaped scene
beams. An example of a collimated beam reconstruction densitometer
measurement illustrating a limestone plume is shown in the trace of
Figure 34. The hologram used was No. 1564. The location and relative
intensity of the existing limestone cloud is marked on the trace. The
cloud extended from near the south wall of the boiler to a point approxi-
mately 7 feet away from the north wall. The cloud was reasonably well
defined by the densitometer measurement and could also be located and
measured using the ranging telescope.
In examples where a fanned scene beam is used, a single densitometer
scan may not adequately characterize the plume. A multiple scan or
"mappingll technique was used as an alternate. An example of this is shown
in Figure 35 for hologram 1570. Successive densitometer scan traces were
projected into a composite perspective sketch or map. The structure of the
plume in terms of relative density D is readily seen. A photographic enlarge- , ,
ment (5X) made from the reconstruction negative used in the densitometry
mapping of hologram 1570 is pictured in Figure 36. The density structure
in the photograph correlates well with the perspective map of Figure 35.
6.4 INTENSITY MEASUREMENTS AND CALIBRATION
In addition to physically locating and dimensioning a limestone cloud
within the boiler, some assessment of the cloud particle number density is
also desirable. With the present Phase III scattered light holograms of
limestone clouds, it is possible only to infer changes in particle density
through variations in light intensity of the reconstructed scene. The densi-
tometer scans of reconstruction photographic negatives from these holograms
provide a relative measure of light intensity as a function of distance across
the boiler. In essence, the absolute intensity scale factor for the recon-
structed images was lost during the sequence of hologram recording, pro-
cessing and data reduction. Examples of how this loss occurs are discussed
subsequently together with some thoughts on how the intensity scale factor
could be preserved. Once such a calibration technique is established, it
should be feasible to assess the particle number density of a given limestone
cloud based upon a mathematical model of the phenomena under study and a
measurement of the scattered light intensity of the reconstructed image.
-"
'~In holograms 1565 and 1573, two distinct clouds were observed. In
determining the centerline values, only the initial cloud (closest to the
near wall) was considered.
-------
111
-
Figure 34.
-------
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INDICATION OF LASER LIGHT
AT No.4 PRISM
DISTANCE FROM
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5
6
7
8
9
SCAN WIDTH IN INCHES
Figure 35.
Densitometer Traces From a Mapping of Hologram
1570 projected into a composite perspective
'1
Figure 36.
Photograph of reconstructed virtual image of fan beam
scattered light from hologram 1570. Laser light from
the prism 33 ft, 6 in. away is seen as a ball of light
at the bottom of the photo. Note also the lateral cloud
structure. The cloud width is -11. 0 ft.
II
I'
l~
-------
The absolute brightnes s of the reconstructed image is proportional
to the point-by-point efficiency of the hologram and to the intensity of the
illuminating reconstructing beam. Accordingly, if the efficiency of each
holographic plate were known, the illuminating beam brightness could
then be adjusted to allow direct comparisons from one hologram to another.
In addition, the intensity of the scattered light (as a function of distance
coordinates within the scene volume) is proportional to the intensity of the
probing laser scene beam. As will be seen, the overall process is not
linear.
Variations in optical efficiency among several holograms in a series
can be caused by variations in the energy content or coherence of the laser
pulses as well as variations in dark-room processing technique (time,
temperature, developer concentration or depletion, etc.). Although an
optical intensity monitor was included in the laser used in the present
studies, the location of the detector was not optimized in the sense used
here. * For the purpose of quantitatively measuring the total plate expos-
ure' a detector should be located in the reference beam path just in front
of the film. A useful method for normalizing reconstruction beam intensi-
ties among several holograms consists of recording in every hologram an
image point of reference intensity (e. g. , by illuminating a standard reflec-
tance surface with a portion of the reference beam). On reconstruction,
brightnesses within the scene can then be normalized to the reference
intensity point, thus preserving an intensity calibration through the record-
ing, processing, and reconstruction steps. Several types of photometers
exist which could be us ed for making intensity measurements on the hologram.
Making reconstruction photographs of holographic images is another
process in which the intensity scale factor is lost, inasmuch as the total
exposure of the photograph is necessarily adjusted for best photographic
results, depending on the particular photo materials being used. Accordingly,
any negative or print provides only the function of relative intensities in the
scene, at best. Again, the inclusion of a point of reference intensity would
be an aid in preserving a scale factor through these photographic steps. A
further degree in sophistication would be to make intensity measurements
directly from either the real or virtual image of the hologram thus elimina-
ting the intermediate step of producing photographic negatives of the recon-
structed holog ram.
The use of the densitometer typically involves discarding of the inten-
sity scale factor, inasmuch as the instrument is a logarithmically measuring
device, and hence preserves the shape of the relative density function for a
given negative regardless of the absolute density value. Means exist (through
somewhat tedious) for preserving the absolute density of a given negative;
however this has meaning relative to scene intensity only if the density
function 'of exposure of the particular photographic material is known. Here,
again, a reference intensity point could provide a calibration for at least one
point on this function.
*The laser illumination is monitored using a photodiode to detect the output
of the ruby oscillator. See Figure 6.
-------
In the final analysis, one must always begin with a representation
of the holographi.c image which at least displays the relative intensity
function in the scene. In Section 6.3, a great deal of information was
obtained from the shape of the densitometer traces-evidence of limestone
clouds was detected where it could not be readily seen with unaided eye.
In other cases, a dense cloud of material near the entrance port attenuated
the light beam to such an extent that the luminosity of fly ash near the exit
port was noticeably reduced. Accordingly, it becomes obvious that the
information content of the scene is encoded in the shape of the relative
intensity function rather than in absolute local intensities.
What is needed at this point is a mathematical model (derivable from
light attenuation theory and geometrical considerations) which predicts the
shape of the densitometer traces, as function of the fly ash and limestone
concentrations, with reasonable as sumptions made as to size distributions
of the two species. With this model, and using standard curve-fitting
computer programs, the shape of the densitometer traces can be analyzed
to yield nominal limestone concentrations as a function of distance across
the boiler within the path of the probing light beam. ~,
-------
7.
CONCLUSIONS
From the holography studies accomplished during this program, it
has been conclusively established that two-beam scattered light holography
of particulate in an operating boiler (nominal power output of 140 mw) is
entirely feasible. In addition, photometric means of evaluating the recon-
structed holographic images have been developed to the extent that quanti-
tative data as well as qualitative impressions can be obtained. More
specifically, the following may be stated:
(1 )
The presence of limestone plumes or clouds can be
detected over (scene beam) distances of up to 24 feet
of boiler combustion volume. Further, the technique
appears applicable over much greater distances. For
instance, two-beam holograms of scattered light across
the 50 -foot length of the Unit 10 superheater area would
be entirely feasible.
(2)
The recorded limestone clouds can be physically located
within the scene along the laser beam axis. The clouds
can be located using either a ranging telescope or via
densitometer measurements scanning the virtual image
of the reconstructed hologram.
(3 )
Cloud dimensions can be measured and the presence of
voids established and also measured. Accuracy of mea-
surement varies with distance into the reconstructed
scene. It is estimated that at 24 feet (far wall of the
boiler from the observer's station), accuracy is limited
to approximately :f::0. 5 feet. The greatest accuracy is
obtained when making measurements close to the holo-
graphic plate (i. e., toward the near boiler wall) where
:f::0. 1 feet is feasible.
(4)
The holography technique is sensitive to limestone plumes
injected at elevations of 5 and 16 feet below the viewing
(scene beam) ports. The intensity of the recorded clouds
seen in holograms taken with limestone injected from
either location appear similar. Evaluation of the cloud
data suggests that stream tubes within the boiler may
reduce significantly, the degree of plume dispersion
once a basic plume geometry has been established follow-
ing injection. In this regard, it is hypothesized- tha~
velocity profiles (normal to the flow) may strongly mflu-
ence plume geometry.
The limestone plumes or clouds generated by either the
front or rear injection ports varied in overall dimension
considerably. There did not appear to be any significant
repeatability to the cloud size although, admittedly, !he
data sample size is limited. Remarkably more consIstent,
however were the cloud centerline locations with respect
to the w~ll through which the limestone was injected.
(5)
-------
(10)
(6) A significant conclusion from the holographic data is that
voids do occur in the limestone clouds as they ascend
through the boiler. Voids were observed in 28 percent of
the recorded limestone clouds which were reduced for
da ta.
(7)
The thermal cells which were originally observed in
earlier holographic test series were artifically induced
by cold air entering the boiler through the exit viewing
port. When a window was used during later tests. the
thermals were almost always eliminated from the recon-
structed scene.
(8)
With the present feasibility demonstration holograms.
only relative changes in light intensity within a given holo-
gram can be determined. Suitable calibration methods
are lacking at present to make quantitative comparisons
between different holograms. A method has been sug-
gested. however. which should allow comparison of light
intensity variations between two or more holograms
(cloud images) and further. permit estimates of particle
number concentrations. *
(9)
During the recent test program. consecutive hologram
recordings were made (at times) at a rate of one every
1-2 minutes' using entirely manual techniques. This rate
could be increased significantly if desired. Means of
obtaining rapidly sequenced recordings are within the
state of the art (to microsecond intervals if necessary)
but require a more sophisticated camera setup.
The nominal "turn around" time required to record,
develop and reconstruct individual holograms made at
the Unit 10 boiler was approximately 20 minutes. For
the most part, however, recordings were made and
processed in batches. The holograms were then lei-
surely examined at a later time. A reduction in turn
around time to less than 8 minutes is entirely feasible
without any appreciable difficulty.
The acquisition of quantitative hologram data was accomplished at
TRW System facilities in Redondo Beach, California. Subsequent holo-
graphy studies could incorporate means fQr interrogation of the hologram
at the power plant site.
*
Refer to discussion in Section 6. 4.
-------
8.
RECOMMENDATIONS FOR FUTURE WORK
Work accomplished during this program has demonstrated that holo-
graphy is a viable technique for in situ measurements of limestone clouds
injected into a full-scale (140 megawatt) operating steam boiler. The
holographic apparatus and the techniques of operation are sufficiently
flexible to permit the monitoring of limestone plumes from any set of
opposed ports at the current (365-foot) boiler elevation. Further, the
basic equipment may be installed at other elevations on the boiler provided
that opposing ports are or can be made available. Specific recommenda-
tions based upon the results of this work are as follows:
.
Holography should be utilized as one of the primary instru-
mentation methods during the formal limestone distribution
study phase of the dry limestone process evaluation program
at the Shawnee Unit 10 boiler.
.
The holographic technique is most useful for obtaining
instantaneous data concerning plume geometry and struc-
tural detail. Implementation of the technique during criti-
cal phases of the overall limestone distribution should be
especially valuable.
.
The acquisition of holographic data should be time coordin-
ated with the simultaneous monitoring of other boiler and
injection system operating parameters so that direct cor-
relation of results can be made.
.
Future holographic instrumentation at the Shawnee boiler
should make provisions for using wider scene beam diver-
gence (greater lateral coverage of the plume) or, as an
alternative, multiple scene beams to probe more than one
injected lime stone plume at a time.
.
Consideration should be given to developing a suitable
technique for making rapid sequences of exposures on the
holographic plate so that dynamic fluctuations in the injected
limestone cloud may be observed.
Subsequent holography studies at the boiler should incor-
porate a means of hologram calibration s~ch that ab~~lute
light intensity measurements ,may be obtamed to faclhtate
estimates of particle number concentrations in the recorded
scattered light plume images.
A technique for estimating a particle number concentration based
upon measuring the absolute intensity of a hologr~phically .record.ed
scattered light image of a limestone plume w~s d1~cussed In Sect,lOn 6. .4
of this report. It is recommended that w?rk m thIS area ~e, contm~ed m
support of the basic holography study of hmestone clouds mJected mto
the Unit 10 boiler. Successful application of the proposed technique will
provide further quantitative information from subsequent holograms
recorded at the boiler.
.
-------
It is entirely feasible to rapidly scan developed holograms and sub-
sequently use the scan information as input to a computer program that
would calculate.the particle number concentrations and identify the location
of the recorded plume images with respect to a reference wall in the boiler.
The entire data acquisition, reduction and processing function could be
initiated at the Shawnee plant. Formal presentation of the data in tabular
or graphic form might be accomplished within approximately 24 hours for
large quantities of holograms. Specific tests of interest could be accom-
plished in an even shorter period
Because of the potential of the proposed holographic data reduction
method and correspondingly large number of recordings which may be
required in the process of evaluating the limestone distribution as a func-
tion of various (boiler) system parameters, it is recommended that devel-
opment of an automated data handling technique be initiated in support of
future work at the Shawnee Steam Plant.
-------
REFERENCES
1.
T. D. Womble, Jr. and J. T. Reese, liThe Dry Limestone Injection
Process for S02 Control, Part I - Equipment De'scription, Cali-
bration and Operating Experience," paper presented at the NAPCA
Dry Limestone Injection Process Symposium, Gilbertsville,
Kentucky, June 22-26, 1970.
2.
Ibid., "Part II - Preliminary Test Results. "
3.
H. W. Elder, "The Dry Limestone Injection Process for S02
Control, Part III - Test Program," paper presented at the NAPCA
Dry Limestone Injection Process Symposium, Gilbertsiville,
Kentucky, June 22-26, 1970.
4.
Anon., "Sulfur Oxide Removal From Power Plant Stack Gas -
Sorption by Limestone or Lime, Dry Process, II Tennessee Valley
Authroity Report prepared for the National Center for Air Pollu-
tion Control, 1968. p. 3.
5.
G. H. McClellan, "Physical Characterization of Calcined and
Sulfated Limestones, II paper presented at the NAPCA Dry Lime-
stone Injection Process Symposium, Gilvertsville, Kentucky,
June 22 -26, 1970. p. 18.
6.
R. F. Wuerker, "Instruction Manual for Ruby Laser Holographic
Illuminator," TRW Report No. 11709-6003-RO-00 (AFRPL Con-
tract F04611-69-C -0015), February 1970.
7.
Anon., Tymshare Super Basic 2245 "POLYCURV," Reference
Series - Library Tymshare, Inc., Los Altos, California,
February 1969.
8.
B. J. Matthews, R. F. Wuerker and R. F. Kemp, "Holographic
Determination of Injected Limestone Distribution in Unit 10 of
the Shawnee Power Plant, II Progress Report No. 1170. 69-001,
NAPCA Contract CPA 70-4, September 1969. pp. 6-8.
-------
APPENDIX A
THE TECHNIQUE OF HOLOGRAPHY
-------
A single beam of coherent light scattered by small objects was the arrange.
ment first used by Dennis Gabor to demonstrate the holographic principle.!
Fourteen year$ later, a second independent unmodified reference
beam was added by Emmett Leith and Juris Upatnieks.2,3 This rather
significant improvement made possible the recording of scenes with large
contrast ranges, and with large regions of opacities.
The images, fur-
ther, were positives of the original scene.
Since the phase of the re-
constructed wave front was not reproduced across the full area of the
plate, interferometric comparisons between holograms recorded on the
same or separate plates, or between a hologram recording and the real
scene at a later time could be done for the first time.
The simplest form of holography is the version used originally by
Gabor.
A single beam of coherent light is typically passed through the
scene and allowed to fall on a photographic plate.
The plate records
the intensity distribution due to the interference between the trans-
mitted beam and light scattered by the objects in the beam. Although
only a single beam is used, the photographic plate records the super-
position of two wave fronts; namely, the transmitted and the scattered
light. This version is known as IIs.ingle-beamll or Gabor holography, to
distinguish it from the more improved form in which a separate reference
beam is employed.
Even recently, the single beam technique has been used to success-
4,5
fully measure tenuous, distributed microscopic high speed phenomena.
Rather than the filtered light from a mercury arc (used originally by
Gabor). a pulsed ruby laser of 20-50 billionths of a second duration has
been used to illuminate the hologram.
The short duration of the laser
source makes possible the freezing of high speed microscopic phenomena.
-------
Both "single beam" and double beam holography are described by the
same basic mathematical equations.
One specifies the unmodified or reference wave via complex notation,*
as:
~r (x, y, z, t) = Ar{x,y) {exp j[wt - kz + ~r{x,y)]}
where
(l)
Ar{x, y) is the amplitude of the right traveling wave specified
in equation 1.
exp
is the exponential function of the base of the
natural system of logarithms. (e = 2.71828)
j
is
"'-T
k
is the an9u1ar frequency of wave in radians per second
(w = 21ff) .
is the wave number (i.e., k = 21f/A)
w
and
~r (x, y) is the phase of the wave.
Equation 1 describes a wave traveling in the positive z Cartesian
**
direction with a velocity of w/k.
Ideally, the reference is a plane
* Equation (1) is a solution of a wave equation or differential equation
of the fonn:
2 ( 2~ 2
u+ L ~ = 0
ax2 w2 3t2
This type of equation specifies the propagation of electromagnetic
radiation (i.e., light) in free space, as well as propagation
acoustic energy.
** The wave travels to the right with a velocity found by setting the
argument of the exponential equal to a constant and differentiatins;
namely, ~~ = f = C, where C for electromagnetic radiation C is the
velocity of light.
-------
wave of constant amplitude and phase.
For such a case,
$ (z, t) = A exp j[wt - kz]
r r
(2)
The scene beam is represented similarly, but will in most cases
consist of amplitude and phase terms which are functions of the x, y
position, namely:
$s(X, y, z, t) = As(x, y) {exp j[wt - kz + $s(x, y)]} (3)
Holography is concerned with the superposition of these two coherent
waves on top of one another and the recording of the resultant stationary
interference pattern on a piece of film or photosensitive material. At
the plane of the photographic plate, the two waves are superimposed one
on top of the other.
$s + $r
(4)
The intensity in this region of superposition is simply:
I = ($s + $r) ($s + $r)*
(5)
where * denotes the complex conjugate of the sum of $ and $ .
s r
complex ~otation, the intensity at the plate is simply:
Thus, in
* * *
I = $s$s + $r$r + $r$s + $r $ s
(6)
which on expansion can be shown to reduce to the following real expression:
I = IAs(X' y)12 + IArl2 + ArAs(x, y) {cos $r - $z(x, y)}
(7)
-------
which is a mathematical expression for the fact that the superposition
of two traveling waves results in a stationary distribution in space.
One next assumes an ideal photographic plate; namely,
the amplitude transmission is proportional to the exposure.
one in which
For such a
recording media,
T a = Ko - Kl It
(8)
where Ko and Kl are constants of the film, I is the intensity of the
light, and t is the exposure time.
After exposure to the intensity pattern given by either Equation 6
or 7, the film will have a transmission (substitution of Equation 6 into
8) of
* * * *
Ta = Ko - Kl [~s~s + ~r~r + ~r~s + ~r ~s ]t
(9)
If the developed photographic plate is next reilluminated by a beam that
is a duplicate of the original beam ~r then the following light distribu-
tion pattern will emerge from the other side.
* * * *
~out = ~rT = Ko~r - tKl[~s~s ~r + ~r~r ~r + ~r~r~s + ~r~r ~s ]~r
(10)
Gathering terms, one can identify the following:
(a)
*
[Ko - tKl~r~r ]~r
as the reference wave transmitted through
the hologram (11)
*
(b) - tKl[~s~s ]~r
as noise transmitted in the direction of
the reference beam (12)
as the complex conjugate of the original
scene, and (13)
*
(c) - tKl[~r~rJ~s
-------
*
(d) - tK1 [t/Jrt/Jr ] t/Js
as the reconstructed waves i.e.s the one
which is identical in phase to the original
and of amplitude proportional to the orig-
i na 1. (14 )
Thus, the mathematical argument predicts that the hologram will re-
construct a wave proportional to the original scene wave whenever the
hologram is rei11uminated by a duplicate of the original reference wave
front. Recent experiments have verified the truth of this Aristotelian
argument. 6,7
In the case of the Leith-Upatnieks configuration, the two beams
pass through one another at different angles. Mathematically, this is
equivalent to the addition of a linear phase factor.
for the scene the following expression:
One could write
t/Js = As(x, y} {exp j[wt - kz + ~s + ax]}
(15 )
where the quantity aX gives a phase which increases uniformly in the x
direction. The reference is the same as before (i.e., equation 1).
Summing the two waves, taking the intensity (as in equation 5), multiply-
ing by the transmission of the film, and multiplying again by the ref-
erence, yields the same equation (i.e., equation 10).
Collecting terms,
one obtains the two that are of interest, namely, the virtual image:
* .
- tK1[t/Jrt/Jr ]t/JsEJax
and the conjugate image
* .
- tK [t/J t/J]t/J -Jax.
1 r r s E
-------
The quantity -aX is interpreted as a wave propagating at minus the angle
of the original wave.
The two beam arrangement has the feature that it separates the real
and conjugate wave constructed from the hologram.
In the case of Gabor
or single beam holography. the "scene" is created by scattering of the
reference beam by objects within the beam and between the source and the
photographic plate.
In the two beam hologram arrangement, the reference
is separately supplied.
In the Gabor case, the scattering scene, however, modifies the ref-
erence beam so that the phase and amplitude of the reference no longer
are simple functions.
The theory says that to identically recreate the
original scene beam, the plate must be reilluminated by a beam identical-
ly equal to the reference beam at the time that the hologram was record-
ed.
If the reference is a complex function of both amplitude and phase,
the hologram is somewhat encoded, with the result that resolution suffers.
Two beam holography does not suffer from this difficulty.
The operation and resolution of a simple Gabor hologram arrangement
can be understood from the schematic shown in Figure A-I. The upper pic-
ture shows the recording of the hologram of light scattered from a point
source (~s) by a parallel reference wave, (~r)' If the extreme rays
scattered by the point source cross those of the reference at an angle
a, then the hologram will have a numerical aperture of Sin e. 8
The schematic in Figure, A-I also shows the reconstruction of the real
* *
(tKl[~r~r ]~s) image and the conjugate image (tKl[~r~r~s ] ) from the
-------
DIRECT RAY'
LAS ER
BEAM
FIGURE A-I. -
F
~
POINT
SUBJECT
PHOTOGRAPHIC PLATE
F
REAL
IMAGE
'lIRTUA
IMAGE
,,-'
,,-"-
-,-'
","
ORDERS OF
DIFFRACTION
"
'....
"
"
Single beam (Gabor) hologram of a point subject, showing the
recording of the hologram in the upper schematic and the re-
construction of the virtual and real images from the hologram
in the lower schematic. The angle e determines the numerical
aperture of the hologram and the resolution of the reconstruct-
ed images. .
-------
hologram.
In terms of diffraction from periodic gratings, the former is
known as m = 1 order while the latter is m = -1.
The resolution of the
reconstruction is determined by the angle subtended by the virtual and
real image, provided the phase of the reference is recreated exactly over
the full aperture. Thus, for this ideal situation, the resolution is
the same as with any other optical apparatus,9 namely:
R = A
2 Sin 8
(16 )
In the case of the original hologram, the superposition of the scene
and reference rays creates stationary regions of constructive and destruc-
tive interference.
These can be shown to be separated by an amount equal
to:
A
6 = 2 Sin 8/2
( 17)
Thus, in the ideal case, the resolution
R = 6 S~ n 8/2
S1n 8
( 18)
which in the limit of small angles ~ 6/2, namely the resolution of the
reconstruction is equal to half the resolution of the photographic fi 1111.
The arguments are highly idealized in that it was assumed that the
reference beam used to rei11uminate the hologram was identically equal
to the one originally used in the recording.
It can be seen that as the
scene becomes more and more complicated, the reference beam becomes in-
creasing1y encoded.
Duplication is only possible across a small aperture.
Refractive index changes also complicate the background wave by the same
process.
The net result is that the reference beam can only be reproduced
-------
over a small aperture.
This, in turn, reduces the resolution.
To
appreciate this, one can rewrite the resolution (Equation 16) as:
R = ~ ~/F2 + x2
2X V
(19 )
in terms of aperture diameter 2X and the object distance F.
In the limit
of small aperture,
AF
RO« F "'2X
(20)
For example, for 0.69~, the wavelength of a ruby laser, and a hologram
object-distance of 100 centimeters and aperture diameter of 1 centimeter,
resolution is 69 microns. A reduction to 1 millimeter gives a resolution
of 694 microns~
Thus, maximum resolution requires the maintenance and
integrity of the reference beam.
For situations where the beam transmitted through the scene volume
is heavily attenuated, a two beam arrangement is clearly warranted.
The
reference beam can then be piped around the scene and kept simple and
reproducible.
-------
REFERENCES - APPENDIX A
l.
2.
D. Gabor, "A New Microscopic Principle," Nature, 161, 777-778 (1948).
E. N. Leith and J. Upatnieks, "Reconstructed Wavefronts and Communica-
tion Theory", J. Opt.Soc. Am., 52,1123-1130 (1962).
3.
E. N. Leith and J. Upatnieks, "Wavefront Reconstruction with Contin-
uous Tone Objects", J. Opt. Soc. Am., 53,1377-1381, Dec. 1963.
B. J. Thompson, "Fraunhofer Holography", Proceedings SPIE, Seminar
in Depth on Holography, Volume 15, Society of Photo-Optical Instru-
mentation Engineers, 1968.
4.
5.
C. Knox, "Holographic Microscopy as a Technique for Recording Dynamic
Microscopic Subjects", Science, 153, 989-990, 26 August 1966.
L. O. Hefl i nger, R. F. Wuerker, and R. E. Brooks, "Ho 1 ographi c
Interferometry", Journal of Applied Physics, ~, 642-649, Feb., 1966.
6.
7.
R. L. Powell and K. A. Statson, J. Opt. Soc. Am., 55, (612A), 1965,
p. 1956.
F. A. Jenkins and H. E. White, Fundamentals of Optics, McGraw Hill
Book Co., 1950, p. 298.
8.
9.
Ibid.
-------
APPENDIX B
USAF 1951 RESOLVING POWER TEST TARGET
-------
The resolution of an optical instrument is basically its capacity for
imaging fine detail. Stated another way. resolution is concerned with the
ability to measure differences based upon the comparison of two very close
sources of light. Ultimate resolution is the measure of the close$t dis-
tance two points of light can be placed and still be recognized as being
individual points.
The linear resolution for an optical system may be numerically expressed
in terms of lines per millimeter. Resolution devices or targets for evalu-
ating optical systems often consist of geometric patterns which may be
"read" or interpreted. A commonly accepted patterned target is the U.S.Air
Force 1951 Resolving Power Test Target, which is defined by Military Stand-
ard 150-A. This resolution target, shown in Figure A-l, consists of an ar-
ray of three-line "patterns." The width of a line is equal to the width of
the spacing between lines in each pattern. Further, the length of each
line is five times its width.
A grouping of two patterns set at right angles to each other is termed
an "element" of the test target. The elements are arranged in increasingly
smaller sizes. These elemental size changes in the USAF 1951 Target are
defined by a geometric progression based upon the sixth root of 2, or .if2I.
Stated another way, the number of lines per millimeter doubles every sixth
target element.
The target elements are arranged in columnar form. Each column is
numbered (from ~2 to 7) and each element within a given column is identified
by another number (1 to 6). Therefore, an element on the target is described
by a column number and a "row" number. The accompanying table (see Figure
B-1) provides a listing of the number of lines per millimeter for each ele-
ment. For the 1951 target, the largest element corresponds to 0.250 lines
per millimeter while the smallest is 228 lines per millimeter.
-------
In reading a resolution chart, one identifies the smallest element in
hich the three-line pattern can be distinguished. The column and row num-
ers of this element (for example, column 3, row 1 or 3-1) are noted and
he cbrresponding number of lines per millimeter for the element is then
onvenient1y obtained from the Table in Figure 8-1. For element 3-1, the
a1ue is 8.00 lines per millimeter.
It is also possible to assign an equivalent particle width (or diam-
!ter) from the resolution target. Remembering that the width of each line
ind adjacent space are equal, and taking the reciprocal of the measured
~eso1ution in lines per millimeter, the period of the line spacing is ob-
tained (millimeters per line). One-half of the period then, is the smallest
:>bject which may be discerned. Thus, if a USAF 1951 target can be IIreadll
to column 3, row 1, the line spacing is 8 lines per millimeter. This is
equivalent to 1/8 = 0.125 millimeters per line. One-half of this value is
0.0625 millimeters (width of the line only) or 0.0625 millimeters x 1000
microns per millimeter = 62.5 microns. This would be the smallest width or
diameter of an object which could be individually identified by the optical
system in question.
-------
Group Number (Column Number)
Element No. 4 5 6 7
(Row No.) 2 3
-2 -1 0 1
. 4.00 8.00 16.0 32.0 64.0 1Z8.
1 0.250 0.500 1. 000 2.00
Z.24 4.49 8.98 17.95 36.0 71.8 144.
Z 0.280 0.561 1. 12
1. 26 2.52 5.04 10. 1 20. 16 40.3 80.6 161.
3 0.315 0.630
2.83 5.66 11.3 22.62 45.3 90.5 181.
4 0.353 0.707 1.41
1.59 3.17 6.35 12.7 25.39 50.8 102. 203.
5 0.397 0.793
1. 78 3.56 7.13 14.3 28:51 57.0 114. 228.
6 0.445 0.891
.,
rJ
~ If ~~i.
D
:~.,-;;
'" . .
ci' Qi
:.. '-4:2.
.
I:fl
;,.
Figure B-1.
Photograph of a USAF 1951 Resolving Power Test Target.
The table above the photograph indicates the number of
lines per millimeter for each element on the target.
-------
APPENDIX C
DA T A SUMMARY SHEETS
UNIT 10 LIMESTONE INJECTION TEST HOLOGRAMS
-------
()
I
N
Hologram Recording Data
Line Power Li mes tone Reco rd Fi 1 ters Used Deve 1 ODment laser Pulse line
No. Date Time Output Injection Rema rks No. No. 70 CS-2-58 N.D. Time HRP Output Quality Test Conditions & Remarks No.
,.., lb/hr Min. Ratio mV
1. 3- 4- 70 No (50-243) No None None 4 4:1 155 No Fi 1 ter. Scene beam centered on port. 1.
limes tone 1322 Filter 50-243 saturated. Checkout test only.
2. 1325 X 8 135 Direct scene beam onto plate. Good "fingerprint" of
scene beam. light flame fogging of film plate. 2.
Scene "fingerprint" plus scattered light .
3. 1327 4 135 all around. 3.
4. (50-243) Scattered 1 ight. 50-243 fi 1m. Film saturated - 4.
1330 2 hologram barely visi51e.
5. 1700 140 1331 160 Best of series on 3-4-70. 5.
3.5 (Possible thermal cells)
6. 1339 2.0 185 Multiple camera shutter operation. 6.
Hologram not as bright as 11331.
7. 3-5-70 138 1378 X 0.3 4 Multiple N.D. Filter - partially covers reference beam. 7.
- Pulse Conclusion - Severe fog.
N.D. Filter Dartially covers scene beam. Can focus 8.
8. 138 1380 0.3 5 175 on edge of filters. Test not conclusive.
9. 138 1381 None 5 185 USAF 1951 target in scene 28.5" from hologram, back- 9.
lighted by scattered light. Good to Col. 3, Row 2.
Limestone started at Ground glass over inlet boiler port, 32'-3" from
10. 3- 6- 70 0925 141 0902 hrs. ~stem 1385 5.5 150 10.
failed at 0 7 hrs. film pl ate.
11. 0935 140 1386 5 135 Duplicate of 11331. Scattered light. 11.
\ery bright hologram.
12. 1422 141 -7000 Rear injection ports 1391 5.5 170 8right hologram. Some thermal distortion of beam 12.
(28%) near exit. No visible plume.
1392 5.5 220 Scene beam distortion near right edge. 13.
13. 1425 -140 .., 7000 No plume of limestone can be discerned.
14. 1433 <140 .., 6000 1393 5.5 187 Many "thermals". No apparent plume. 14.
.
15. 1435 <140 - 7000 I . 1394 7 165 No image. Plate fogged. 15.
16. 1435 <140 ,., 7000 I 1395 6 145 Weak hologram. Periodic incoherence? 16.
, Focusable light and dark spots. Many "therma 1 s" 17.
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Hologram Recording Data
Line Power Limestone Reco rd Filters Used Deve 1 Dement Laser Pulse Line
No. Date Time Output Injection Remarks No. No. 70 CS-2-58 N.D. Time HRP Output Qua 11 ty Test Conditions & Remarks No.
"'" 1 b/h r Min. Ratio mV
18. 3-6-70 1455 -132 ,.. 6000 Limestone Injection 1397 X 5.5 1:4 170 Uniform but weak exposure. No distinct limestone 18.
throu?~4~ar ports cloud. lots of .. thermal s ".
19. 1458 132 - 6000 .. 1398 5.5 195 Same as #1397 19.
20. 1459 132 ,.., 6000 1399 5.5 170 Same as #1397 20.
21. 1510 132 - 6000 .. ' 1400 2.0 180 Changed scene beam to hit closer to port. 2l.
No image. Plate fogged.
22. 1512 -133 - 6000 ' 1401 7.2 162 Faint image. Image of particle can be seen thru 22.
lower left-hand corner (slag?)..
23. 1513 ...133 ,.. 7000 . .. 1402 6.2 168 Several "rays". both 1 i ght and dark. 23.
lots of scattering. Good hologram.
24. No 1 imestone on Glass fil Osc. & Cyl. ("spreader") lens installed at entrance to last 24.
3-11-70 1617 140 - 3-11-70 test series. 1474 ter as Unknown 125 Amp 1. prism box before boiler. 'Amplifier removed for repair -
windnw new flash lama. Wealc imaoe.
25. 1620 1475 170 Same as #1474. Slightly stronger image. 25.
26. 1626 1476 200 Spreader lens removed. Slightly weak image. 26.
Scattered light can be observed.
27. 1629 1477 135 Same as #1476. Weak image. 27.
28. 1724 1488 170 Osc. & Spreader lens again installed. Amplifier installed in 28.
Ampl. laser. Ref. beam alignment on plate is somewhat off.
29. 1732 1490 1~0 Spreader lens out. Moderately good image. Beam 29.
scatters light entire distance (24').
30. 1816 141 1491 5.0 1:4 150 Spreader lens in. Soot blower lK-1 going. Moderately 30.
good fan shaped image. Light scattered across' 24'.
31. 1820 141 1492 9.0 1:2 160 Spreader lens out. Soot blower lK-1 going. 31.
No image.~ fog.
32. 1829 128 Start Unit 10 Power 1493 13.0 150 Spreader lens in. Soot blower lK-l going. 32.
Reduction Tests No image. Flamelight fogging of plate.
33. 1838 105 1494 UnmOolln 180 Plate missing. 33.
34. 1852 100 1502/ ~ -150 Double exposure? Lens out. Weak image. 34.
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Hologram Recording Data
Line Power Limestone Record Fi 1 ters Used Deve 1 ODl11ent Laser Pulse Line
No. Date Time Output Injection Remarks No. No. 70 C5-2-58 N.D. Time HRP Output Quality Test Conditions & Remarks
iii 1b/hr No.
Min. Ratio mV
35. 3-11-7( 1855 92 No Uni t 10 Power 1505 X 180 Spreader lens out. Good image. Uniform ~cattering 35.
Limestone Reduct ion of light across beam.
36. 1906 86 ~' MW :.. Mm. I'ower Lens in. Good bright hologram. Apparently uniform
4 coa 1 burners 1506 9.0 1: 1 160
Lean O/F. particulate (fly ash) distribution. Som; "rays" visiblE 36.
37. 1915 85 Flame Transparent 1513 3.5 1:2 160 Lens in. Plate fogged by accident. No image. 37.
38. 1921 85 Opposite boiler tube 1516 7.0 1:2 160 Lens in. Good image. Many" r~ys " . Scattering 38.
wall clearly visible. over 24 ft.
39. 1923 85 1517 0.3 6.0 1: 1 140 Lens in. Weak image. 39.
40. 1926 85 1518 6.0 1:2 150 Spreader lens out. Reconstruct~ but image is
somewha tweak. 40.
41. 1928 84 1519 0.3 6.0 140 Lens out. Moderately good image even with 41.
. N.D. 0.3 filter.
42. 2006 84 1524 1.0 18.0 150 Lens out. Fai r image. N.D. 1.0 filter in scene. 42.
43. 2010 84 1525 Glass fi1 Lens out. Bright image, uniform scattering,
I ~1~tI~~ 20.0 170 no "thermals". 43.
44. 2012 84 1526 15.0 170 Lens out. Same comments as for 11525. 44.
45. 2013 88 1527 20.0 150 Lens out. Same as #1525. 45.
46. 2027 138 1528 17.0 180 Lens out. Same as 11 52 5. 46.
47. 2028 140 1529 15.0 140 Lens out. Same as 11525. 47.
No Opposite boiler tube Lens out. Bright reconstruction with uniform
48. 3-12-70 0835 -140 Limestone wall barely visible. 1534 13.0 170 scattering. No thermal~. 48.
49. 0847 ..,3000 Limestone thru rear Lens in. Good, bright reconstruction.
ports at 0845. Air 1535 11.0 150
meter at 30%. A lot of scattering. 49.
50. 0850 8000 1536 10.0 150 Lens in. Same as #1535. 50.
51. 0858 141 7500 1537- Lens in. Moderate fog. Will reconstruct but
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, Hologram Recording Data
Power LilllflStone Record Filters Used Deve100ment Laser Pulse line
Line Date Tilll/! Output Injection Remarks No. No. 70 CS-2-58 N.D. Time HRP Output Quality Test Conditions' ReNrks
No. No.
III lb/hr Min. Ratio mV
0902 -141 7500 Limestony thfu rear Glass fil Lens in. Very good, bright hologram.
52. 3-12-70 ports onM' esW- 1539 X ter as 11.0 1:2 140 Uniform scattering. 52.
11535-15 ,Air window
meter at 30%. Lens in. Very good hologram and uniform 53.
53. 0910 6000 I 1542 11.0 150 scattering.
54. 0918 6500 1543 5.5 175 Lens out. Bright reconstruction. Uniform. 54.
55. 0920 6500 Opposite boiler tube 1544 5.5 170 Lens out. Same as '1542. 55.
wall not visible.
1.0 in Lens out. Bright as 11542. Can focus on edge 56.
56. 0922 7000 1545 top of 5.5 160 of N.D. filter.
Isce.nf!
57. 0925 7000 1547 l 5.5 140 Lens out. Same as 11545. 57.
W&2.0
58. 0928 6500 1548 in top 12.0 165 Lens out. Same as 11545. 5B.
f scene
59. 0931 6000 1549 ~ 12.0 150 Lens out. Same as #1545. 59.
60. 0948 6000 1550 7.0 150 Lens in. Bright reconstruction. Apparently 60.
uniform scattering. Many "rays".
61. 0951 6000 Limestone supply 1552 X 10.0 140 Lens in. Same as 11550. 61.
nearly out.
~i'O~~ Lens in. Same as 11550. Rays appear
62. 0953 6000 1553 of scene 8.0 175 uniformly spaced. 62.
only
63. 0954 6000 1554 . 8.0 150 Lens in. Same as 11550. 63.
Lens in. Very good, bright hologram. One of 64.
64. 0956 6000 1555 12.0 160 best quality of series.
1556 X 13.0 180 Lens in. Very good reconstruction. 65.
65. 0958 - 5000 Similar to 11555.
1005 4000 1558- 3.0 170 Double exposure (lens in.). Plate fogged but 66.
66. 1559 will reconstruct.
Some limestone feed 1560 6.0 140 Lens in. Very bright hologram. Little evidence 67.
67. 1008 5000 thru bottom rear of 1 imestone.
Inort~ on Iv.
Limestone injected thr 7.0 150 Lens out. Gas laser beam barely visible and ex-
68. 1108 11 ,000 front 4 ports on ly. 1562 tinguished at times when visually observed. 68.
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Hologram Recording Data
Line Power Limestone Record Fil ters Used DeveloDment Laser Pulse Line
No. Date Tillie Output Injection Rema rks No. No. 70 CS-2-58 N.D. Time HRP Output Quality Test Conditions & Remarks No.
f4r/ lb/hr Min. Ratio mV
69. 3-12-70 1110 -140 Limestone injected Glass fil- Lens out. Bright hologram. Evidence of a cloud 69.
,... 7500 thr~ front 4 ports 1563 X ter as 11.0 1:2 160 at front of boiler.
only. Air meter 25% wi ndow
70. 1113 1.0 in 13.0 150 Lens out. Similar to #1563. Good hologram 70.
1564 top of recons tructi on.
scene
71. 1115 1565 J 12.0 155 Lens out. Bright reconstruction but difficult to 71.
define limestone cloud edges. Similar td" #1563.
1.0 & 2.0 72.
72. 1117 1566 intopof 10.0 170 Lens out. Similar to #1563.
scene
73. 1120 Lens out. Bright reconstruction but difficult to 73.
1567 10.0 165 precisely identify cloud.
Lens in. Cloud visible'- has structure and limits. 74.
74. 1122 ,.,11 . 000 1568 6.0 140 Rays also visible. Good hologram.
Lens in. Very thin limestone cloud. Bright rays seen 75.
75. 1124 1569 5.5 155 in reconstruction in foreground. Good hologram.
Lens in. Dense limestone cloud. Edges can be defined. 76.
76. 1125 1570 7.5 120 Cloud appears to have some structure. Good hologram.
Lens in. Bright cloud with edges and structure. This 77.
.77. 1127 1571 5.5 130 is one of the best holograms of this series.
7.0 150 Lens in. Similar to #1570. Note the one predominate 78.
78. 1129 1572 "ray" of light in scene. Good hologram.
6.5 160 Lens in. C1Qud visible and has structure and 79.
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