TEST AND EVALUATION REPORT (Sanitized) IMAGE COMPARISON MICROSTEROSCOPE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04560A007300010035-0
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 44
• Document Creation Date: December 28, 2016
• Document Release Date: March 26, 2003
• Sequence Number: 35
• Publication Date: September 1, 1972
• Content Type: REPORT

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TECHNICAL
PUBLICATION
NATIONAL PHOTOGRAPHIC
INTERPRETATION CENTER
TEST AND EVALUATION REPORT
25X1
IMAGE COMPARISON MICROSTEREOSCOPE
Declass Review by NIMA / DoD
CONE IDENTIAI
NPIC/R-10/72
SEPTEMBER 1972
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This document contains information affecting
the national defense of the United States,
within the meaning of Title 18, sections
793 and 794, of the U.S. Code, as amended.
Its transmission or revelation of its contents
to or receipt by an unauthorized person is
prohibited b}' law.
CLASSIFIED BY: 55-0001
Exempt from General Declassification Schedule
of E.O. 11652, Exemption Category: SB(1),(2),(3).
AUTOMATICALLY DECLASSIFIED ON
APPROVAL OF THE DCI
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t IV ~ ~ NPIC R-10
TECHNICAL PUBLICATION
TEST AND EVALUATION REPORT
25X1
IMAGE COMPARISON MICROSTEREOSCOPE
SEPTEMBER 1972
25X1
Test and Evaluation Branch
Engineering Support Division
NATIONAL PHOTOGRAPHIC INTERPRETATION CENTER
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ABSTRACT
1. INTRODUCTION
2. SUMMARY OF TEST RESULTS
3. CONCLUSIONS AND RECOMMENDATIONS
4. DESCRIPTION OF EQUIPMENT
5. TEST DETAILS
5.1 Acceptance Tests 11.
5.2 Operational Evaluations - 25
5.3 Engineering Analysis and Evaluation - 26
Distribution
LIST OF ILLUSTRATIONS
1
e Comparison Microstereoscope
a
I
iv
.
Figure
m
g
Figure 2.
Figure 3.
Image Comparison Microstereoscope
Controls
Typical Range of Human Eye Iris
Diameters Superimposed on Photo-
hs of ICM Exit Pupils
ra
8
27
Figure 4.
g
p
Oscilloscope Traces of Relative
Light Versus Time
30
TABLES
tical Resolution (line pairs/mm)
O
3 :2
_
Table 1.
p
Table 2.
Anamorphic Settings
33
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The Image Comparison Microstereoscope (ICM) was tested
and evaluated at NPIC between August 1971 and May 1972. Ac-
ceptance tests, operational evaluations, engineering evaluation,
and viewing mode evaluation were conducted within this time
period.
The instrument provided all viewing modes that were required
by the specification. The optical system performed well. The
instances in which the ICNI did not meet optical specifications
did not appear to hamper the use of the instrument by PIs in
their evaluation of its operational capability.
Some human-factor deficiencies were noted which would be
corrected in future instruments. The ICM exhibited reasonable
reliability and presents no problems to internal, routine
maintenance with the exception of drive belts for some of the
optical switches.
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1. INTRODUCTION
1.1 Background
The prototype Image Comparison Microstereoscope (ICM) is
a direct viewing optical instrument with four film chip stages
and eight viewing modes. It was developed in response to a
need to compare different pairs of stereo imagery, This is the
reason for having four stages. An additional purpose was to
provide binocular monoscopic viewing modes for experimentation.
The viewing modes or ways of examining the various combinations
of film chips are defined in section 4.2.
1.2 Test Objectives
The ICM, received in August 1971, was tested by the NPIC
Test and Evaluation Branch (TEB) to determine if it met the
contractual requirements. There were 21 contractual require-
ments for the acceptance testing, which was completed in
January 1972. Engineering evaluation observations were made
during this and other testing. Minor additional engineering
tests were conducted by TEB in April 1972. The objective of
the engineering evaluation was to evaluate the optical, elec-
trical, and mechanical design of the total instrument. To
assist TEB in the engineering evaluation, an independent con-
25X1 tractor was employed to conduct two studies of the
ICM during ecem er 1971 and January 1972. The objective of
one study was to produce a performance evaluation of eight
viewing modes, both stereoscopic and binocular monoscopic
(see section 4.2) using PIs. An additional objective was to
determine how the ICM could best be utilized in support of
photointerpretation activities and how much improvement it
25X1 offered over conventional display devices. The objective of
the second stud was to determine the extent to
' which human-factor prlncip es were incorporated into the design
of the ICM.
Operational evaluations were conducted independently by
five operating components within their own
environment. Photographi_ ...,...____~~_ ~~_~ furnished to these
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components, by TEB, to demonstrate the ICM's capability. A
questionnaire was also prepared to solicit answers as to
whether the ICM could contribute to their normal operation
and, if so, which modes were most useful. The operational
evaluations started in February 1972 and were completed in
April 1972.
1.3 Training
The complexity and sheer number of controls on the ICM
make it necessary to provide fairly extensive training. The
more than ten people involved received one day of lectures
and more than one day of hands-on training (or its equivalent).
(A few untrained subjects were used for specific and limited
tests.) The training was provided
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2. SUMMARY OF TEST RESULTS
2.1 General
The ICr--~ test results show it to be a well-liked and useful
instrument.
2.2 Acceptance Tests
The optical features of the ICM are generally within 10
percent or better of the reduirement. The exceptions were the
duality of focus of Stage 3 at low zoom settings, the optical
resolution of Stage 1 at high magnification, and the adeduacy
of illumination for the 1.42X objective at high zoom settings.
Switching to the condenser system designed for the 4X objective
can alleviate the latter deficiency. The mechanical features
of the ICM essentially meet reduirements. The functional
features such as image rotation and interpupillary adjustment
generally more than meet reduirements with the exception
of the flicker (blink) feature. The maximum flicker rate
is less than 15 Hz where 30 Hz was specified. This con-
tractual deficiency is softened by the fact that other
tests indicate that a slower flicker rate is desired than
the 0.5 Hz minimum that was contractually reduired. The
ICM more than meets safety reduirements although. the lamp
housing surfaces in the kneespace went 21? higher than
the specified upper limit of 105? F.
2.3 Other Evaluations
An engineering analysis and evaluation plus five operating
The enginee
nducted
i
a
v
g
.
ons were co
component evaluat
hts 25X1
hli
lii
The
tion included two studies g g
of these evaluations are:
o Operation of the ICM is complex enough to reduire
formal training of an operator to attain efficient use.
This training was accor!plished by means of a separate
contract with the manufacturer. Proficiency on the
instrument will decrease if use is not constant but
can be regained with minimum effort when the need
arises.
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o The Blinking Stereo* viewing mode and a monoscopic
version of it have been judged the most useful while
the Color Comparison* viewing mode and an automatic
version of the Blinking Stereo* mode have been judged
the least useful.
o An objective performance ranking lists the
Blinking Stereo* viewing mode an a monoscopic version
of it as the top two modes and an automatic version
of Blinking Stereo* and Split Field Stereo* as the
bottom two. The differences between any two modes were
not large enough to be conclusive, however.
o The minimum flicker rate should be lower. The switch-
ing arrangement should be arranged so that both ima
are presented for a time period in each cycle.
commented that blink (flicker) systems with fas
and decay times should be evaluated.
o There is a need to handle larger film sizes than the
prototype ICM will accommodate.
o Some operational components considered the pantograph
arms and locking connections between stages unsatis-
factory because they could not move the rear stages
without disturbing the alignment of the front stages.
Emphasis on the proper setup procedures during training
should relieve this complaint. The "joystick" controls
for fine positional adjustments of the front stages
are beyond the psychomotor capabilities of most people
but such adjustments are easily made by grasping the
front stage directly.
o The off-axis resolution is reasonably good. However,
there is significant degradation in resolution off
axis when 2.OX anamorphic magnification is used.
Single asterisks throughout this document refer to the
definitions in section 4.2.
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o Anamorphic magnification of up to 1.5X was used to
achieve stereo with one pair of dissimilar photographs,
enabling an experienced photogrammetrist to discover
two buildings that were not otherwise detectable.
Furthermore, other objects were found to be large
boulders and positively not buildings.
o Focusing to the point of blur on both sides of the
optimum focus is not always possible.
o The ICM has been judged of average reliability and no
problems are expected in routine maintenance with the
exception of drive belts. There were three malfunc-
tions in 9 months and one belt had to be replaced
twice. These belts, which control optical switches,
are difficult to replace.
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3. CONCLUSIONS AND RECOMMENDATIONS
3.1 The ICM has been accepted by the operational components
as a useful instrument.
3.2 The anamorphic magnification helped achieve useful stereo
fusion. However, at the 2.OX maximum setting, it does cause
significant degradation of resolution in the off-axis portions
of the field of view.
25X1 3.3 human-factor evaluation yielded a list of 35
recommen ations for improving performance, ease of operation,
and operator safety and comfort. It is recommended that they
be considered in detail when planning further development.
3.4 The "joystick" controls for fine stage positioning are
neither useful nor needed and should be omitted.
3.5 TEB considers that the three "PIC" belt failures indicates
a design deficiency and recommends that appropriate corrective
action be taken.
3.6 The somewhat inconclusive ranking of the viewing modes may
have been affected by deficiencies in the prototype. This
should be considered when planning further development.
3.7 Efficient use of the ICM requires about 2 days of train-
ing. Maintenance of operator proficiency requires frequent
use or a review of training.
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4. DESCRIPTIOPI OF EQUIPMENT
The ICM (Figures 1 and 2) is a desk size, direct viewing
device with four stages with 5- by 5-inch viewing areas
(larger film chips can be accommodated). Optical switches
enable a single operator to view any stage binocularly,
certain combinations in stereo, and any combination in visual
superimposition. Sets of fixed and movable masks permit
various split field comparisons of the film chips. The
field of view is split vertically so that one film chip
or stereo pair is visible in the left portion and another
is visible in the right portion. The operator can cause
the high intensity stage lamps to turn on and off sequentially
using manual or automatic electrical switches. This is
referred to as blinking and is used in the various superimposition
modes including superimposition of stereo pairs. Ratio
control knobs make it possible to change the "OFF" portion
of the "BLINK" cycle to be dim instead of completely dark,
Pantograph-linkage systems are provided for both the
left and the right pairs of film stages. The linkage systems
can be unlocked to allow each stage to be moved independently.
Suitable stereo conjugates on the left or right stages can
be scanned in stereo when a pair of stages is locked together.
The left pair of stages is visible in Figure 1. Normally the
left stereo conjugate would be placed on the front stage and
the right conjugate on the back stage. The second set of
stereo conjugates would be placed in the opposite order on
the front and back stages on the right side of the ICM. The
linkage systems are designed to enable the operator, while
remaining seated, to move the rearmost left and right stages
by means of joysticks mounted on the front stages. The left
and right linkage systems are visible in Figure 2. The
pantograph arms attached to each film stage prevent rotation
of the stage during translation. Each stage can be rotated
about its center. The front two stages have knobs for fine
control of the stage rotation.
Pechan prisms in each of four optical trains permit
rotation of the film images. Anamorphic systems in each
optical train provide for differential magnification (up
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to 2X) between perpendicular directions in the planes of
the film images. Each optical train has an independent
zoom system to vary the magnification by a factor of from
0.7 to three, Each stage has interchangeable objectives
of 1.42X and 4.OX magnification. With the lOX W.F. eyepieces
the total magnification range is about lOX to 120X.
Interchangeable condenser optics are designed to provide
proper illumination for the interchangeable objectives.
Individual electrical controls vary the intensity of the
tungsten filament halogen lamps. Concentric with these
controls are the ratio control knobs which vary the intensity
of the associated lamp during the "OFF" portion of the
"BLINK" cycle. Four small fluorescent tubes around the
periphery of each stage provide background illumination to
assist in the initial placement of the film chips.
For convenience, numbers have been assigned to the four
film stages. The left rear stage is #1. The left front stage
is #2. The right rear stage is #3. The right front stage is
#4. The optical trains associated with the stages are some-
times referred to as channels. The stage and channel numbers
used throughout this report refer to the numbers as given
above .
The ICM weighs 750 pounds, is 41 inches deep by 51
inches wide, and is mounted on 5-inch diameter caster wheels.
It requires less than 10 amperes of electricity at 60 Hz
and 108 to 128 volts.
4.2 Operating Modes
These are the contractual definitions of the required
viewing modes. (Asterisks in other parts of this document
refer to these definitions.)
o Alternating Stereoviewing* technique consists of
studying a stereo pair, switching mechanically
to another stereo pair, and detecting changes by
memory recall. (The switching is done by manual
operation of two optical switches.)
o Superimposition* technique consists of binocularly
viewing two images simultaneously and detecting
differences due to lack of register.
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o Split Field Comparisons technique requires a
split field whereby two nonstereo images may be
viewed side by side.
o Mask Edge Scanning* technique (monoscopic) will
allow split field masks to be moved in synchronism
over the photographs occluding one and exposing the
other.
o Alternate Occlusion (Flicker)* method consists of
means to electrically flicker the images to accent
changes. (First, one condenser system brightly
illuminates one monoscopic image of an optically
superimposed pair. Then the illumination from that
condenser is greatly reduced as another condenser
brightly illuminates the other monoscopic image.)
o Color Comparison* technique consists of color
coding the superimposed images with filters to
enhance detection of differences due to lack of
register.
o Split Field Stereo* method will present two stereo
models simultaneously to the operator's field of
view, enabling side-by-side comparison.
o Blinking Stereo* method permits alternate occlusion
of the two stereo images. (Performed by manual
operation of a switch connected to the lamps.)
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5.1 Acceptance Tests
Optical Features
5,1.1 Image Quality
Design Objectives - Specifications
Image quality should be of the very best, commensurate
with that of high quality laboratory microscopes, and essen-
tially free of aberrations and flat of field.
Using two square grids (distortion free) obtain stereo
fusion and record a description of any false sense of depth.
In the superimposition modes, check for nonalignment. Check
for on-axis or other astigmatism. Check with both sets of
objectives, over the zoom range, through both eyepieces, to all
possible stages, and with all eight operating modes.
No significant aberrations affecting image quality were
detected. The flatness of field is covered in section 5.1.6
(Field of View).
The ICM meets this requirement.
5.1.2 Optical Resolution
Design Objectives - Specifications
A resolution of at least eight lines/mm per power of
magnification at lOX shall be provided. The system must re-
solve 300 lines per mm with the low power objective (1.42X)
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used at a maximum magnification (for the whole system) of
42.6X. The required resolution is 600 lines per mm with the
high power objective (4.0X) used at a maximum system magnifica-
tion of 120X. The lines/mm per power at any magnification shall
not be less than a linear rate of change between these two
extremes.
Focus at maximum zoom magnification in the center of
the field of view using the diopter tester 25X1
25X1 and a suitable resolution target. Recor t e me ian
rea ing of readings by three observers for each case.
The results of 36 median readings at the lowest magni-
fication was that all 4 channels are within one resolution
element (about 120) of the requirement. At the highest magni-
fication the results varied between one and two resolution
elements below the requirement except for Channel 1 which is
more than 24o below the requirement. Twenty-four percent is
considered greater than the experimental error for this kind
of measurement. Typical values for the highest magnification,
on axis, are shown in the table.
Channel
Optical Resolution**
Magnification
(Maximum)
(line pairs/mm)
Eyepiece
Left Right
1
115X
364/325 409/364
2
117X
459/459 NA
3
119X
459/459 515/515
4
121X
N/A 459/459
**The first number in the Eyepiece columns is for resolution
target bars perpendicular to the observer's eyebase. The second
number is for bars parallel to the observer's eyebase.
At the intermediate magnifications (about 27X and 47X),
72 median readings showed only one out-of-specification reading.
Except for Channel 1 the ICM meets this requirement.
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5.1.3 Stage Illumination
Design Objectives - Specifications
A high-intensity condenser-type source shall be pro-
vided beneath the surface glass plate of each chip stage. This
source shall be designed for and mated with the microscope to
insure maximum performance from the optical viewing system.
At full intensity, the high-intensity source must provide
adequate illumination of a film area with an average density
of 2.5 units as viewed through the optical system at both eye
stations while operating at a magnification of 120X. All
other magnification settings shall be equally well illuminated.
The source for each stage shall operate at a temperature be-
tween 3500K and 5500K. Means shall be provided for continuously
varying the illumination from SOo to 1000 of full intensity
of each independent high-intensity source. Such reduction shall
not bring the apparent Kelvin temperature below 3500K. Sep-
arate controls varying the intensity of illumination of each
separate stage plate shall be provided. In addition, a Ratio
Control will control the intensity in the dim portion of the flicker
cycle in the Alternate Occlusion* mode. Two condensing systems
will fill the largest useful field (20 mm) and the largest use-
ful aperture (0.106NA) of the 1.42X relay objective and the
largest useful field (7 mm) and the largest useful aperture
(0.202NA) of the 4X relay objective.
Measure the correlated color temperatures at 50% and
1000 of full intensity from each stage with each condensing
system using the Gamma Scientific Inc. Model 3000 spectroradi-
ometer. Measure the light intensity through the eyepieces at
various magnifications relative to that at 120X. Obtain an
opinion from three PIs as to the adequacy of the illuminator
when viewing imagery (of the maximum available average density
in the FOV) at 120X. Check the other features.
Test Results
The 38 measurements of color temperature ranged from
4090K to 5360K. Two condenser lens systems are provided for
the high-intensity light source for each stage. The last lens
surface of each condenser lens system for the 1.42X objectives
has been partially converted into a diffusing surface, which
essentially changes the character from a condenser-type to a
diffuser-type light source. The numerical apertures (N.A.)
are 0.1 for the 1.42X objective and 0.2 for the corresponding
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condenser. The N.A.'s are 0.2 for the 4X objective and
0.1 for its corresponding condenser. The PIs agreed that
the illumination through the 1.42X objective (and film imagery)
from the matching system is questionable (marginal) when
used at 40X. The average density of the imagery ranged
from 1 density unit (d.u.) to no more than 1.7 d.u. No
imagery (black and white) of 2.5 d.u. (standard diffuse
transmission density) was available. Changing to the condenser
for the 4X objective or going to lower magnifications produced
satisfactory illumination. The condensers do fill the fields
of view as required. The Ratio Controls meet the requirement.
Another test showed that using the Pechan prism to rotate
the image can decrease the light level by as much as 300.
This light level decrease would degrade the adequacy of
illumination still more.
Conclusion
The ICM does not meet this requirement.
5.1.4 Focus
Design Objectives - Specifications
Independent focus shall be provided for each chip stage.
Both a coarse and a fine focus shall be provided. A means
shall be provided to adjust for the differences in focus between
the left and right eye of the operator.
Check at one nominal interpupillary distance setting.
Adjust the eyepiece foci on the discrete numerical digits .and
on one rear stage in a binocular mode. Focus on the other
stages with the independent coarse and fine foci of the objec-
tive lenses. Check with both sets of objectives, over the
zoom range, through both eyepieces, to all possible stages, and
with all eight operating modes.
Independent coarse and fine focus controls were provided
for each of the four sets of objectives. Both eyepiece tubes
can be focused independently. The quality of focus was good
except for the low zoom settings of Channel 3 (the right rear
stage) .
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It is questionable whether the ICM meets this require-
ment .
5.1.5 Magnification
Design Objectives - Specifications
The instrument shall provide zoom-type, continuously
variable, lOX to 120X magnification by means of zoom elements,
lOX fixed eyepieces, and self-contained interchangeable objec-
tive lenses. The total range in magnification is to be lOX
to 42.6X with the 1.42X first relay objective, the 0.7X to 3.OX
zoom system, and the lOX eyepiece. The total range in magnifi-
cation is to be 28X to 120X with the 4X first relay lens, the
0.7X to 3.OX zoom system, and the lOX eyepiece. Between 28X
and 42.6X the magnification ranges overlap.
Count the number of divisions of a stage micrometer
(as seen through the eyepiece) that match a suitable number
of divisions on a scale 10 inches from the other eye. The
ratio of distances is the linear magnification. After one or
more such measurements, intercompare with both sets of objec-
tives, over the zoom range, through both eyepieces, to all
possible stages, and with all eight operating modes.
Test Results
The ICM is within about 50 of the requirement.
Conclusion
Essentially meets the requirement.
5.1.6 Field of View
Design Objectives - Specifications
The widest, usable, flat field of view that can be
optically obtained is a design goal. The maximum field coverage
of the low power objective (1.42X) is to be 20 mm. The maximum
coverage for the high power objective (4.0X) will be 7.14 mm.
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Record the visible range on a stage micrometer at three
equiangular directions across the field of view. Measure the
field flatness at 0.8 of the eyepiece field position in terms
of the refocusing required from the on-axis position. Check
with both sets of objectives (at the lowest zoom setting)
through both eyepieces, to all possible stages, and in the
stereo and superimposition modes.
The most frequent values for the fields of view were
18.6 mm and 6.9 mm taking all viewing modes together. These
values are within 70 of the requirement, although the entire
field of view is not always usable. Up to 0.01 inch refocusing
movement of the 4X objective lens is required to bring the area
at 0.8 of the field of view into focus. From 0.05 to 0.08
inches refocusing movement of the 1.42X objective lens is re-
quired for all but Channel 3, which cannot be focused on the
area at 0.8 of the field of view.
It is questionable whether the ICM meets this require-
5.1.7 Anamorphic
Design Objectives - Specifications
The optical system for each of the four inputs shall
incorporate anamorphic correction that is continuously variable
from l.OX to 2.2X. The direction of anamorphic stretch is to
be rotatable through 360?.
Use a grid on one film stage and a scale on another
suitable stage. In the superimposition or split field modes,
direct anamorphic magnification comparisons can be made. Ro-
tate the axis of anamorphic stretch through 360? or to its
limits and record.
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The 12 measured maximum anamorphic magnifications were
2.OX with two exceptions of 2.06X. The anamorphic correction
controls had unlimited rotation of the stretch axes. The ICM
is within 100 of the requirement.
Conclusion
Essentially meets the requirement..
Mechanical Features
5.1.8 Construction
Design Objectives - Specifications
Construction shall meet the highest standards of micro-
scope design.
Inspect for interfering scratches, digs, and stains
that are visible during use. Inspect for any lint, grease,
oil, dirt, or scum that interfere with visual use and that can-
not be easily cleaned off. Formulate and record opinions on
the structural ruggedness of the microstereoscope and its
components.
Nothing appeared to interfere with visual use. The
structural ruggedness of the microstereoscope, and its components
appeared to be satisfactory to the test engineer.
The ICM meets this requirement.
5.1.9 Stage Translation
Design Objectives - Specifications
Each chip stage shall have independent translation in
the X and Y directions to allow adjustment of relative chip
positions. Independent stage travel shall not be less than
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+3.55 inch in both the X and Y directions. A common trans-
lating motion shall be incorporated to allow the left pair or
the right pair of stages to be moved simultaneously in the X
direction and in the Y direction. The stage motion must have
low friction and must be smooth, positive, and chatter free,
Operation shall be by means of a fine control.
Measure the range of independent X and Y motion of each
stage by observing (at low power) a scale on the stage using
the crosshairs of the diopter tester or edge of the field of
view as the reference mark. Repeat for the other stages.
Record opinions of smoothness, positiveness, and ease of move-
ment of the stages. (NOTE: Stage rotations should be at 45?
for these tests.)
The average value of 17 measurements is within to of the
required +3.55 inches. The smoothness and ease of movement
were judged to be good. The positiveness of stage movement
was good except for a backlash of 0.01 to 0.05 inches. The
mechanical joysticks that were provided as the fine controls
were unsatisfactory. However, fine control was found to be
unnecessary.
Conclusion
The ICM essentially meets this requirement.
5.1.10 Film Hold-Down
Design Objectives - Specifications
Film chip hold-down will be by means of a 1/4-inch
glass pressure plate over the film. Its weight will provide
sufficient force to hold the film flat without spring loading
and without scratching or marking the film. The glass will
be of sufficient optical quality so as not to degrade the
imagery .
Mount and demount typical film chips on each stage.
Check the film chips for new scratches and marks. Check the
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thickness of the plate. Check the flatness of curled film
chips that have been kept rolled around a pencil.
Conclusion
The ICM meets this requirement.
Functional Features
5.1.11 Split Field
Design Objectives - Specifications
A means for viewing in the Split Field (nonstereo)
Comparison* mode will be provided. A means for Mask Edge
Scanning* (traveling split field) and a stationary Split Field
Stereo* mode will be provided. The Split Field Stereo* images
will be oriented correctly (in relation to the two front stages)
when the image rotation controls are at their nominal zero
positions. It shall be a design goal that the Mask Edge Scan-
ning* image will also be oriented correctly (left-right).
Correct left-right orientation of the images in the Mask
Edge Scanning* mode is not obtainable for the stage combinations
1-4, 2-3, and 2-4. Otherwise modes operate as required.
Conclusion
The ICM meets this requirement. (The left-right orienta-
tion was only a design goal.)
5.1.12 Image Rotation
Design Objectives - Specifications
Optical image rotation of 360? shall be provided for
each of four input images.
Test Results
Image rotation for three of the channels is unlimited.
Channel 1 has a range of rotation of 580?.
Conclusion
The ICM more than meets this requirement.
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5.1.13 Image Selection
Design Objectives - Specifications
It shall be possible to view the images as follows:
left front, left rear, and right rear through the left eye-
piece; left rear, right rear, and right front through the right
eyepiece. This system of optical switching shall provide the
maximum optical movement from a minimum control movement.
Stages 1, 2, and 3 can be seen through the left eyepiece
as required. Stages 1, 3, and 4 can be seen through the right
eyepiece as required. The control movement involves a 79? ro-
tation of one or two 5.8 cm levers.
Conclusion
The ICM meets this requirement.
5.1.14 Independent Zoom
Design Objectives - Specifications
The optical image path for each of the four photos shall
provide independent zoom magnification.
Test Results
The four zoom systems do operate independently.
Conclusion
The ICM meets the requirement.
5.1.15 Interpupillary Adjustment
Design Objectives - Specifications
An adjustment for variation in interpupillary distances
between 52 and 74 mm shall be provided together with an easily
readable graduated scale to indicate actual millimeter setting.
The interpupillary adjustment shall be provided with a positive
lock.
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Use typical settings for the eyepiece and objective lens
foci. Suspend a ground glass screen (or equivalent) over the
eyepieces so that small sharp exit pupils are made visible.
Measure the distance between the centers of the exit pupils.
Check with both sets of objectives, over the zoom range, through
both eyepieces, to all possible stages, and with all eight op-
erating modes.
The measured interpupillary distance was 51 mm minimum
and 74 mm maximum for all configurations. A graduated milli-
meter scale and a positive lock were provided.
The ICM more than meets this requirement.
5.1.16 Flicker
Design Objectives - Specifications
An electrical means for occluding one or both images
alternately will be provided. The rate of occlusion will be
variable (by the operator) between 0.5 Hz and 30 Hz. A form
of this alternate occlusion will be usable for stereo compar-
ison. A ratio control will control the intensity in the dim
portion of the flicker cycle in the Alternate Occlusion* mode.
Full counterclockwise rotation of the BLINK RATE control will
hold all four lamps on continuously. The intensity of each
lamp will be dependent upon the setting of its INTENSITY con-
trol. When the STEREO BLINK switch is moved to its ON position,
the left stage lamps are paired together and the right stage
lamps are paired together. With the AUTO./MAN. switch in the
AUTO. position, the two selected lamps (or pairs of lamps) will
blink on and off at the frequency set by the BLINK RATE control.
In the MAN. position the LEFT/RIGHT switch will light the left
or right lamp or pair of lamps.
Test Method
Measure the flicker rates with an optical sensor and
an oscilloscope. Observe the oscilloscope trace while varying
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the Ratio Control to judge whether or not it works. Check the
other features.
Test Results
25X1
The flicker rates varied from 0.58 to 0.63 Hz (16
measurements) at the slow end and from 14.0 to 14.3 Hz (8
measurements) at the fast end. The flicker rate was easily
variable between these values. The Ratio Control and other
features do operate. Full counterclockwise rotation of the
BLINK RATE control did not hold all four lamps on continuously.
Conclusion
The ICM does not meet this requirement.
Safety Features
5.1.17 Shock Hazard
Design Objectives - Specifications
The ICM must be grounded and free of all hazards.
Test Method
Measure the leakage current with the
Leakage Current Tester in all electrica y signs scant
configurations. The microstereoscope will be connected to a
25X1 Ground Fault Circuit Interrupter.
ou is unit e tripped, the shock hazard will be re-
evaluated.
The highest leakage current measured was 0.29 ma with the
power switch turned off, the electrical plug reversed, and the
ICM ungrounded. All other electrical configurations yielded
less leakage current. The most stringent ASA requirement (for
portable devices) is 0.5 ma. The ground fault circuit inter-
rupter set to trip at 3.4 ma was never tripped during the
extensive acceptance tests.
The ICM more than meets this requirement.
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5.1.18 Warning Light
Design Objectives - Specifications
A warning light must be provided to show when the power
supply to the unit is switched to ON.
Conclusion
The ICM meets this requirement.
5.1.19 Heat
Design Objectives - Specifications
The temperature on the normal operational surface of
the instrument shall not exceed 105? F after operating at maxi-
mum intensity over a 24-hour period in a room with an 80? F
ambient temperature. The temperature of a film chip with an
average density of 2.5 placed on the stage and illuminated at
maximum intensity will not exceed 120? F.
Place disposable film chips having average densities of
2.5 density units emulsion side up on each stage. Operate at
maximum intensity for 24 hours in a room or enclosure at 80? F.
(NOTE: Preliminary temperature measurements during the 24-hour
operating period may show that the film temperature is so far
above or below the 120? F limit that this test may reasonably
be terminated.) Probe the normal operating surfaces for the
hottest areas and get estimates of the surface temperatures
that exceed or are close to 105? F.
The hottest parts of the ICM that the operator is likely
to contact are the lamp housing plates in the operator's knee-
space. The temperature of the left one exceeded 126? F. All
other positions, including the 2.5 d.u. test film chips were
well within the requirement.
The ICM does not meet this requirement because the lamp
housing plates exceed 105? F.
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Convenience Features
5.1.20 Image Selection Indicator
Design Objectives - Specifications
Discrete numerical digits to indicate to the operator
which of the images he is viewing will be provided. They will
be sandwiched between two glass cemented substrates so that
dust particles in the image plane will be eliminated. The
indicators must remain in focus throughout the magnification
range and must not substantially intrude into the field of view.
View each numerical indicator with one eye and compare
with a scale that is 10 inches from the other eye. Set each
anamorphic ratio at its maximum setting. Rotate the axis of
anamorphic stretch through 360?. Record any intrusions into
the fields of view and any defocusing of the numerical indi-
cators.
The numeral 1 for Channel 1 intrudes from loo to 20%
into the field of view as the axis of anamorphic stretch is
rotated. The numeral 3 for Channel 3 goes partly out of the
field of view as the axis of anamorphic stretch is rotated.
The numerals disappear when covered by masks and when backed
by dark imagery. This disappearance is considered unavoidable
without undue expense and is relatively unimportant.
The ICM does not fully meet this reauirment because of
the Channel 3 numeral going partly out of the field of view.
5.1.21 Background Illumination
Design Objectives - Specifications
Backgound illumination shall be provided for each of the
stages to facilitate orienting film chips on the stages. Four
T5 4-watt fluorescent lamps shall be located around the per-
iphery of the free aperture of all four stages.
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Attempt to obtain specific orientations of the film chips
using background illumination only. Check the switch and lamps.
Test Results
There are two switches per stage and four T5 4-watt
fluorescent lamps per stage. The background illumination is
sufficient for orienting film chips on the stages except when
the color filters are in place.
Conclusion
The ICM partially meets the requirement.
5.2 Operational Evaluations
Each of the four operating components of 25X1
and APSD/TSG used the ICM for a week or longer. enera y,
the personnel who evaluated the ICM were from the trained group
(referred to in 1.3) or were in turn trained by them.
The ICM provided a variety of viewing modes for evaluation.
The opinions of the operating components varied as did those
of the personnel within the components. However, they generally
ranked six of the eight contractually required viewing modes,
in order of usefulness, as:
Split Field Stereo*
Split Field Comparison*
Superimposition*
Mask Edge Scanning*
Blinking Stereo*
Alternate Occlusion (Flicker)*
The Alternating Stereoviewing* mode was not evaluated, ap-
parently because the Blinking Stereo* mode was so much easier
to use. The Color Comparisons viewing mode was not used in the
operational evaluations. It had been previously concluded
that large contrast differences between two film coverages
tended to obscure differences due to missing objects. There-
fore, change detection was easier without the color filters.
The filters were not made available to the operating compo-
nents during the operational evaluations. One component
tested a four-image superimposition viewing mode for signal
to noise enhancement with no success.
This subjective ranking should be used with caution as
should the objective ranking given in section 5.3.5.
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The operating components were dissatisfied with the
present arrangement of pantograph arms and locking connections
between stages for two reasons. Some PIs with short arms
found it difficult to move the rear stages independently of
the front stages while looking through the eyepieces. How-
ever, proper emphasis on the setup procedures during training
should eliminate the need for independent movement of the
rear stages. There is some slight relative motion between
linked stages which hinders scanning in stereo. However,
stereo scanning is not a requirement of the prototype ICM,
especially at high magnification.
Two of the components commented on the need to handle
larger film sizes than the prototype ICM will accommodate.
The blink (flicker) rate was generally considered to be too
fast even at its lowest rate. One component reported that the
eyepieces did not stay firmly in place when being focused.
Another component stated that the eyepiece unit should be
redesigned so that existing filar eyepieces can be inserted
and used. A number of other human-factor type comments were
made. However, all of the operating components concluded that
the ICM was a good instrument.
5.3 Engineering Analysis and Evaluation
5.3.1 Exit Pupils
An introduction to this subsection is necessary to warn
the nontechnical reader that the photographs (Figure 3) of
the exit pupils are not directly relatable to what the eye
sees at the film plane. In fact, it was found that with the
ICM controls set for the worst case (Figure 3. a), the edges
of the four fields of view at the film plane were misaligned
by less than 2 percent of the 1.32 mm diameter of the fields
of .view at 115X total magnification.
The exit pupil can easily be made visible by placing a
diffusing screen at a distance above the eyepiece equal to
the exit pupil height. The size and position of the exit
pupil or ..pupils can then be measured directly or photographed.
Figure 3 consists of enlarged photographs of the exit pupils
from the right eyepiece of the ICM for various settings.
Figure 3.a and b show the effect of the anamorphic magnifica-
tion control. Figure 3.a and c show the extremes of exit
pupil superimposition occurring with image rotation changes.
Figure 3.d shows the degree of superimposition for the base
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a) Zoom Max.
Objective 4.OX
Anamorphic Mag. 1.
b) Zoom Max.
Objective 4.OX
Anamorphic Mag. 2
Figure 3. Typical Range
enlargement) a) and b)
tion controls set at th
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25X1
configuration (image rotation controls set at their nominal
zero positions). Figure 3.e and f show the respective exit
pupil sizes for the 1.42X objective at high zoom and the 4.OX
objective at low zoom (about 47X and 27X). Note that the
range of exit pupil sizes for the 4.OX objective of the
ICM is 0.6 to 1.8 mm. The 1.42X objective at low zoom gives
1.9 mm. Note also that the separated exit pupils shown
in Figure 3.a, b, c, and d fall within an area smaller than
the usual sizes of the human iris as given by the Human
En ineerin Design Guide for Image Interpretation Equipment,
dated August 1971 (p. 4-10).
The effect of the separated exit pupils could be noted
whenever the observer moved his eye an appreciable amount
from the optical axis. The imagery on the stage correspond-
ing to whichever exit pupil was masked by the observer's iris
would disappear from view while the other stage imagery would
remain in view.
The exit pupil for stage #4 remained in the same position
when the image rotation control was moved through its range.
However, the exit pupils for the other three stages traced
circles of appreciable size as their respective image rotation
controls were moved, indicating the existence of some residual
misalignment.
It has been suggested that a reasonable criterion for
exit pupil separation might be that their centers fall within
a 2 mm diameter circle. A study of this problem is planned
under NPIC sponsorship.
The cutoff of the exit pupil for stage #2 (shown in
Figure 3. a) was studied. A quick check of the optical resolu-
tion showed a nearly 50 percent decrease when stage #2 was
in the worst position (image rotated about 150? from the
nominal zero). This vignetting has since been corrected.
5.3.2 Automatic Blink
The ICM Operation Manual explai set up
the Blinking Stereo* (called A tern ate Stere and
Alternate Occlusion (Flicker)* modes for automatic blinking of
the condenser lamps.
The normal expectation would be that an electronic
system for interrupting the illumination to a stage would
25X1
25X1
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approximate a square wave. The large amplitude, lower
frequency traces in Figure 4.a and b do not meet this
expectation. In addition, Figure 4.a and b show that at
the higher flicker (blinking) rates the light level ampli-
tude severely decreases and the light level ceases to go to
zero. Because the users generally desired a slower flicker
rate than was provided on the ICD~, these deficiencies may
have no operational effect. However, an improved version of
the automatic blink system may well create a need for the
higher blink rates.
No provision was made for varying the time of overlap
between the stages that are to be alternately illuminated.
Such provision may be needed if slower flicker rates are
provided for future models. The contractor's proposal cited
the need for some overlap.
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Stage ~+
~AI~I
~wIW1'~rwlM-,i~IM~ ~wwtwwwu
a) Trace speed: ? cm~sec
Flicker rates: 0.6 and l~+.l Hz
Stage 1
b) Trace speed:
10 cm~sec
Flicker rates:
2.3 and l~+.l Hz
Figure 4. Oscilloscope Traces of Relative Light Levels versus Time.
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The off-axis resolution readings were made at 0.7 of
the distance from the center of the field of view to the edge
of the field of view. The off-axis readings listed in Table
1 were made variously at the top, bottom, left, and right
parts of the field of view. The acceptance criteria assigned
to the on-axis contractual requirement is based on the exper-
imental error associated with optical resolution measurements.
The experimental error is one or two elements on the 1951
USAF Tribar target. This target is based on a 6 2 ratio
between elements. This ratio yields 24 percent for a two-
element difference. Therefore, the on-axis contractual
requirement was decreased by 24 percent to give the acceptance
criteria that are listed in Table 1, sixth column.
Due to the importance of both off-axis resolution and
the anamorphic adjustment feature, a fairly extensive sampling
of data is listed in Table 1. Comparison of the on-axis 2.OX
anamorphic magnification column with the acceptance criteria
and the 1.OX columns shows that the ICM either meets the
criteria or is only slightly worse with anamorphic magnifica-
tion than without. A similar comparison for the off-axis
readings with no anamorphic stretch shows that the ICM either
meets the criteria or is only slightly worse off axis than
on axis. In the off-axis case with 2.OX anamorphic stretch,
9 out of 24 readings do not meet similar conditions. There-
fore, the ICM is deemed to have significant degradation at
0.7 of the field when maximum anamorphic magnification is in
use.
The fact that the ICM has only this much degradation of
optical resolution was unexpected. However, a rationale can
be developed which partially explains this phenomenon. The
1951 USAF Tribar target is based on sets of bars having a 5:1
length-to-width ratio. The anamorphic magnification changes
this ratio because it is a one dimensional magnification. It
is well known that long bars or lines are more easily resolved
by the eye than are short ones. Therefore, when the direction
of the anamorphic stretch is such that it lengthens the image
of the bars, the effect of the eye is to resolve finer resolution
elements than would be the case if the length-to-width ratio
had been kept-constant. When the direction of anamorphic
stretch magnifies the width of and the spacing between the bars,
it is reasonable to expect the eye to resolve finer resolution
elements despite the adverse change in the length-to-width
ratio of the bars. This extra one dimensional magnification
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is not incorporated in the report as a change in the total
magnification of the system. Resolution readings using the
1951 USAF Tribar target are based on a 5:1 length-to-width
ratio and are of unknown validity for other ratios.
5.3.4 Anamorphic Magnification
For this evaluation a pair of low altitude photographs,
which could not rightly be called stereo conjugates, were
used. These photographs were placed on stages #1 and #2 of
the ICM. The ICM was set up as shown in Table 2.
Stage #1
Stage #2
Total Magnification
12.5X (nominal)
lOX (nominal)
Anamorphic Magnification
1.05X
1.5X
Orientation of Anamorphic
Stretch
10 ? to 12 ? CW
about 15 ? CCW
Image Rotation
150? CW
135? CW
The test subject (an experienced photogrammetrist, but un-
trained on the ICM) and the test engineer could see stereo
which was not possible before. With these settings the test
subject distinguished two buildings not seen without stereo
fusion. Furthermore, other objects were found to be large
rocks and positively not buildings.
5.3.5 Viewing Modes Evaluation and Human-Factor Studies
Boeing
The viewing modes of the ICM are not simple to set up,
and the uses of these various modes may not be apparent to
the untrained PI. Consequently, TEB requested a structured
test to insure that selected modes would be used and a
statistical determination of the value of each could be made.
This was to be done in addition to a human-factors study and
the normal NPIC operational evaluation. Experienced PIs who
are accustomed to using stereo techniques were used as test
subjects. The problems to be worked on the ICM were solicited
from operational components
33
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25X1
25X1
This work was done) under contract 25X1
with NPIC. The results are given in a two-volume document,
DK-820, dated March 1972: Image Comparison Microstereoscope _
(ICM), Volume I - Operational Suitability Evaluation (SECRET);
and Volume II - Human Factors Evaluation (Unclassified).
Volume I contains material on the uses of the ICM in
support of PI activities and the measurements of improvement
over a conventional technique. It states that training on
the ICM is essential for efficient operation. Even a well
trained operator must have review material available if he
or she has not used the ICM frequently or recently. The
performance of selected viewing modes in change detection was
evaluated. Some of the viewing modes which were required by
the development contract (e.g. Alternating Stereoviewing*)
were excluded from the viewing mode evaluation.
Limited resources, o in test planning and PI time, were
available. Those modes which were not extensively used
and evaluated were considered to be adequately 25X1
covered by tests on similar mo es. Two new versions of
the Blinking Stereo* viewing mode were evaluated as the
contractor's experience indicated their potential value.
(Note that the viewing mode terminology has been converted
from that of the report to that of the development contract,
section 4.2.) Ho ever, the results overlapped to the extent
that one should be cautious in using them for decision
making. In addition to the objective performance data,
the contractor gathered subjective data during the performance
tests and some specific applications. The ranking (combined)
from the most useful to the least useful is:
Blinking Stereo*
Monoscopic version of Blinking Stereo*
Mask Edge Scanning*
Alternate Occlusion (Flicker)*
(Conventional**) 1540 Light Table/Zoom
240 Microstereoscope
Split Field Stereo*
Automatic Version of Blinking Stereo*
One of the operating components commented that selection of
the 1540/240 combination for the standard of comparison could
lead to misinterpretation of the test results because their
PIs choose from a variety of PI tools those most suited to
each problem.
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The contractor had previously concluded that the Color
Comparison*viewing mode would not be useful for change detec-
tion and therefore it was excluded from the viewing modes
25X1 evaluation by PIs also concluded that the ICM is a
special purpose viewing evice, not a replacement for the
Zoom 240 Microstereoscope. In addition to the four-stage
version of the ICM, a two-stage version with Alternate Oc-
clusion (Flicker)* and Mask Edge Scanning* viewing modes
would be useful for PI activities. PIs should use the
stereo capabilities for determination of the structure of
complex equipment, looking for differences between objects
of the same class, and identification of unknown objects
by comparison with known objects, especially when working
at the resolution limit of the imagery. Monoviewing modes
should be used when simply detecting changes between successive
photographs.
25X1 Volume II of thel lstudy contains 35 recommendations
to improve the human-' actor characteristics of the ICM. To
indicate the extent to which human-factor principles were used
in the design of the ICM, the more important recommendations
will be cited here followed by the positive comments.
o Improve the exit pupil alignment if possible.
o Add a variable aperture to reduce the field of view
to aid in viewing small objects.
o Increase the illumination level for the low-power
objectives.
o Evaluate a blink (flicker) rate system with fast
rise and decay times.
o Make a reticle eyepiece available as an aid in align-
ing images.
o Provide a better method of moving the rear stages.
o Objective lens focusing should be adjustable to the
point of blur on either side of the point for optimum
focus.
The good human-factor features that are incorporated .are:
o Provision of a useful headrest.
' o A nominal magnification range of lOX to 120X (the
entire range was used).
o Anamorphic magnification.
o Optical rotation (was essential).
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o Color coding and numbering of the film stages and
controls.
o Stage linkage made it possible to regain stereo with
little effort after the stages were moved up to
several fields of view.
5.3.6 Reliability and Maintainability
During approximately 6 months of average use, three FCS
quartz halogen lamps were replaced. Lamps of this type have
the relatively short life at maximum intensity of 50 hours.
However, the ICM limits the maximum socket voltage to extend
lamp life.
The pantograph arms and locking connections between
stages are designed to permit movement of these stages
simultaneously. There is some slight relative motion between
linked stages. The locking devices which tie two stages
together can be adjusted to eliminate any relative motion
not attributable to bearing surfaces and joints in the linkages.
Use of the joysticks intended to make the final positional
adjustments of the front stages, is beyond the psychomotor
capabilities of most people. It requires too much muscular
effort and coordination to force the joystick down in one
direction and simultaneously move it slowly in another direc-
tion. The final positional adjustments were satisfactorily
accomplished throughout the test program by simply grasping
the front stage directly.
The "PIC" belts which change the internal rhomboid posi-
tion failed three times, twice on the left side and once on
the right. They are difficult to replace as extensive disas-
sembly of the ICM is required. Some redesign is indicated to
prevent this from recurring. These belts probably were over-
stressed when an endpoint of the rhomboid travel was reached
and the actuating levers were forced an additional distance.
It should be noted, however, that the ICM has been used extensively
for training as well as for testing of its performance. The
ICM is sufficiently complex that the number and types of failures
experienced is considered to indicate average reliability. ,
The Equipment Performance Branch at NPIC judged that routine
optical, electrical, and mechanical maintenance of the ICM
will present no problems.
Approved For Release 20+99'/09/1+~E~IA~RBP78B04560A007300010035-0
 Approved For Release 2003/05/14 :CIA-RDP78B04560A007300010035-0
Approved For Release 2003/05/14 :CIA-RDP78B04560A007300010035-0
 Approved For Release 200~1~1~~~~pP78B04560A007300010035-0
Approved For Release 2008P03~~~+E~I~DP78B04560A007300010035-0