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Optical characteristics, with image tube removed |
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|  MIL-P-63332(AR)
4.6.7 Dielectric strength. Perform this test in accordance with Method
301 of MIL-STD-202, utilizing standard measuring equipment. Dielectric
strength shall be in conformance with the requirements of 3.9. This is an
in-process test that is performed with the components specified in 3.9 removed
from the circuitry. The inspection records for each periscope shall indicate
the results of this test.
4.6.8 Optical characteristics, with image tube removed. Position the
-
periscope on a holding device incorporates the necessary holding features
of the mounting plate assembly specified in 4.5.2.3.1.1. Unless otherwise
specified, the image tube shall be removed from the periscope and the clear
filter shall be positioned in the optical train. The test values for all
characteristics shall be recorded and be made part of the inspection record.
NOTE:
Unless otherwise specified the inspection of the periscope shall be
conducted in an atmosphere that is controlled for temperature,
humidity, and contaminates that would adversely affect the head
assembly or body assembly when separated and not assembled as a
periscope.
4.6.8.1 Contrast transfer on-axis, objective system. Perform this test
using a 2870 100% Kelvin (K) light source, diffuse screen, frequency
pattern (see Figure 1), collimator, an S-20 extended red photo-detector with
slit (see Figure 2), and an "X-Y" recorder set up and oriented as in Figure
3. Position the photo-detector in the tube cavity of the periscope utilizing
an appropriate adapter. Focus the image of the frequency pattern at the
slit. Adjust the "X-Y" recorder for zero level by blocking the entrance of
all light to the photo-detector. Measurements shall be made at 5 frequencies
in the image plane. Position the photo-detector on-axis and advance the fre-
quency pattern, in a horizontal direction, through the five frequencies at a
constant rate such that no signal dampling due to response time of the photo-
detector occurs, and obtain recordings similar to that shown in Figure 4.
Calculate the on-axis contrast transfer for vertical lines using the formula
W - B from measured data. Record the contrast transfer values for the
W+B
vertical lines. Rotate the frequency pattern and slit 90%. Measure, calcu-
late, and record the on-axis contrast transfer values for the horizontal
lines. Contrast transfer on-axis shall conform to the requirements specified
in 3.10.1.1a.
Special care must be taken before test data is made to avoid possible
NOTE:
introduction of contrast transfer losses resulting from the instrument.
4.6.8.2 Contrast transfer off-axis, objective system. Perform this test
in sequence to the test in 4.6.8.1 utilizing the testing equipment and test
method specified therein. Off-axis measurements shall be accomplished by
translating the microscope objective and slit (Figure 2) perpendicular to the
optical axis without refocusing. Measure, calculate, and record the off-axis
contrast transfer values for the vertical lines with the microscope objective
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