LETTER (Sanitized)

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A002900020001-9
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 8
• Document Creation Date: December 28, 2016
• Document Release Date: August 30, 2005
• Sequence Number: 1
• Publication Date: May 9, 1966
• Content Type: LETTER

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May 9, 1966
Enclosed is a draft of the technical propo-
sal discussed in our recent telephone con-
versations. I would appreciate your
comments on the technical content and
direction of the effort.
I will submit a formal proposal after we
have reviewed the draft.
Regards,
Declass Review by NGA.
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May 9, 1966
PROPOSAL FOR MENSURATION ERROR ANALYSIS STUDY TASKS
Measurement of extended lengths to submicron
accuracy is a reasonable and attainable goal and
data for cost effectiveness trade-offs is needed.
Mensuration yardsticks of adequate absolute accur-
acy can be produced. To take advantage of them
and to achieve the routine production of-measure-
ments to the final available accuracy requires
progress on a broad front. Specifically, for cost
effectiveness trade-offs of the measuring machine,
we must consider the effect of:
the operator
the film
the environment
and obtain data necessary for these trade-off eval-
uations.
This proposal is. concerned only with the film
and the environment, but the following comments
regarding operator requirements are included for
completeness.
The operator has a significant impact on the
cost effectiveness of the mensuration system. Since
the operator is a gating function it is imperative that
his effectiveness be maximized. Particular attention
must be paid to:
a) Efficiency of the work station.
b) Reduction of fatigue, particularly eye
fatigue in maintaining stereo registration.
c) Applying all operator faculties to achieving
- pointing accuracy.
In addition to the operator, both the film and
the environmental inputs are potentially serious limit-
ations to the effectiveness of a mensuration system.
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The logical approach is that first their magnitudes
be assessed to provide the data for cost the trade-
off decisions. Determination of magnitude data is
the subject of this proposal. Certain of the data
will be determined by making measurements on exist-
ing equipments and it will be-applicable to improv-
ing the performance of that equipment.
The film contributes to mensuration error in
two ways: by physical distortion and by edge defini-
tion. In particular, we are concerned with physical
distortion of the film during the mensuration process
while the film is mounted on the measuring machine.
(Calibrated fiducial marks are relied upon to provide
correction for distortion prior to mensuration.)
Film physical distortion will be principally deter-
mined by transient and steady state heat balance and
humidity conditions and by the physical constraint
of tension rollers and of the platen to which the
film is clamped by vacuum. We propose a study task
three items:
Task 1. "Thermal Environment"
Item 1) An analytical heat balance transient
and steady state mthdhlr.-will be.pre-
pared of film which is vacuum clamped
to a glass platen.
Item 2) An analytical physical restraint model
will be prepared of film clamped to a
glass platen.
Item 3) A parametric study will be made cif
expected dimensional changes of film
vacuum clamped to a glass platen due
to the variations of parameters
established in 1 and 2 above.
In the parametric study attention will also be
devoted to the effect of film graininess on edge
definition.
The environment contributes to mensuration
error (other than by temperature and humidity) by
vibration. The first consideration is to determine
the statistical properties of the building vibration
which constitutes the input disturbance to the
measuring machine. The next consideration is the
effect of the input disturbance on the measuring
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machine and the contribution to mensuration error.
Finally-the necessary vibration isolation must be
determined. We propose a second study task with
three items:
Task II: Vibration Environment
Item 1) Experimental requirements will be
determined for statistical measure-
ment of building vibration, the
statistical experiment design will
be prepared and the technique proved
by making sample measurements. (We
anticipate that customer technicians
will continue the experimental measure-
ments)
Item 2) -Experimental requirements will be
- determined for measurement of resul-
tant vibration levels at the platen
of specific mensuration equipment with
appropriate vibration inputs. The
experiment design will be prepared
.and the technique proven by sample
measurements.
Item 3) Vibration isolation requirements
will be analyzed with due consider-
ation to internally generated machine
vibration and structural resonance.
The proposed work is delineated in detail in
the accompanying task descriptions.
STAT
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May 9, 1966
MENSURATION ERROR ANALYSIS
Proposed Statement of Work by Tasks
0
Task I: Thermal Environment
Item 1. Heat Balance Model
Establish an analytical heat balance model, transient
and steady state, for film which is vacuum clamped,
to a glass platen and illuminated with high intensity
light.
Procedure: Make a literature search for experimental
data o various film coefficients at various optical
densities such as:
a) Thermal coefficient of expansion of
- film and variation with humidity.
b) Thermal conductivity of film.-
c) Emissivity and view factor of film.
d) Convective heat transfer coefficient.
Where coefficients are not reported, derive an
estimated value from known related technology.
Establish the two-dimensional transient temperature
distribution in the film as affected by the above
coefficients and:
a) Ambient temperature and humidity changes.
b)r.'Absorption of radiation from the light
source,
c) Cooling jets of air.
Establish an analytical model for the resulting two
dimensional distribution-of film distortion and the
transient time. constants. Determine test requirements
for experimental verification of the analytical model.
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Item 2. Physical Restraint Model
Establish an analytical model of the physical restraint
of film clamped to a glass.platen by vacuum and under
tension by tension rollers.
Procedure: Make a literature search for experimental
data on various physical constants of film such as:
a) Frictional coefficient between film and
plate.
b) Young's modulus.
c) Poissons ratio.
S
0
d) Tensile strength and ductility.
e) Flexural rigidity.
Where coefficients are not reported, derive an
estimated value from known related technology.
Develop an analytical model for the two-dimensional
film distortion under the appropriate restraints as
related to the free state dimensional change. Deter-
mine the test requirements for experimental verification
of the analytic model.
Item 3. Parametric Study
Make a parametric study of the expected dimensional
changes of film clamped to a glass platen due to
variations in parameter of 1 and 2 above.
Procedure: Results of the analytical models will be
combined in graphical, tabular, and or analytic
equation form to permit ready determination of the
resultant film dimensional changes-due to variation
of inputs and coefficients.
Task II: Vibration Environment
Item 1: Statistical Properties of Building Vibration
Determine the experimental requirements for statistical
measurement of building vibration. Design the statis-
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tical experiments and make sample measurements. (We
anticipate that continued gathering of statistical
data can be accomplished by customer technicians on
a routine periodic sampling basis.) The building
vibration statistical data to be determined is
essential to cost effectiveness trade offs for
measuring equipment design and for vibration isolator
determination.
Procedure: The power spectrum; the average amplitude;
rms amp itude; average 1/3 highest, 1/10 highest and
1/100 highest amplitudes are the statistical proper-
ties desired. The usual vibration measuring or seis-
mic equipment does not produce this information.
It is necessary to convert the time dependent output
of standard seismic equipment to the above statistical
data. One approach is to record the output on magnet-
ic tape, then play the tape through a power spectrum
analyzer. Another method is to make an analogue to
digital conversion of the recorded data and compute
the power spectral density by digital computer pro-
gram. We will determine-availability of seismic
measuring and analysis equipment with suitable
response and amplitude sensitivity. The equipment
interface compatability, filter-and buffer require-
ments,,auxilliary monitoring requirements and digitiz-
ing requirements will be determined. The experimental
set up will be established and sample measurements
taken. The statistical averages will be computed
from the analyzed data.
Item 2: Statistical Properties of Platen Vibration
Determine the experimental requirements for statis-
tical measurement of platen vibration of specific
equipments. Design the statistical experiments and
make sample measurements.
Procedure: The unit vibration response versus
frequency of specific equipments is the most power-
ful and effective engineering tool for design and
specification purposes. Unfortunately, for completed
and installed equipment it is extraordinarily.
difficult to make meaningful measurements of unit
vibration response. Instead, we propose two other
measurements which will produce reliable data. The
first is to measure film platen vibration of specific
equipments subjected to actual building vibration.
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The experimental techniques will be similar to those
discussed in the previous section. The second is to
make a resonance survey of specific equipments when
subjected to artifical controlled vibration inputs.
The usual technique is to place a small exciter on
the floor or on the machine near the floor, sweep
through the desired frequency range and monitor
platen vibration to detect peaks. The testing
should probably be done during building quiet times
and the exciter input must.be larger than building
input. At the resonant frequencies the instrument
structure will be probed to find the offending
resonating members.
In addition to the above experimental activity,
we will investigate possible techniques of measuring
unit response of equipments which are completed and
in place.
S
Item 3: Vibration Isolation Requirements
From the analytical and experimental vibration data
obtained above, the vibration isolation requirements
will be determined. From the vibration resonance
survey of equipments, we will determine what cor-
rective measures are necessary to reduce resonances
and internally generated vibrations.
Fbr certain specific mensuration equipment in design,
we will prepare an analysis of vibration resonance
and amplitude using building vibration power spectrum
as a forcing function.
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