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MIL-PRF-49170B(CR)

4.5.8 Optical transmittance. Measure optical transmittance using optical devices.

Recommend use of procedure of 6.2.i(5). Noncompliance with 3.5.8 requirements shall

constitute a failure.

4.5.9 Deviation. Deviation shall be measured by determining the angle between the plane

of datum A of Figure 2 and the plane of best focus. The plane of best focus is determined by

measuring the flange focal distance of four image points of 3.25 mm field height and 90

degrees apart. Best MTF at 10 cy/mm is used to determine the exact location of these points

with respect to datum A. Deviation is a vector having components in the x and y directions.

The deviation for a single component is determined by the arctangent of the difference in focal

positions for opposite sides divided by the distance between the points. The deviation is then

the square root of the sum of the squares of the individual components. Failure to meet the

requirements of 3.5.9 shall constitute failure of this test.

4.5.10 Optical test conditions. Each imager shall be inspected at an ambient temperature

(see 6.4.2). Tests shall be conducted with blackbody/graybody radiation over the 7.6 to 11.75

micrometer region using the configuration shown in Figure 2. The test collimator used shall

have a wavefront error of less than 4.0 wavelengths (peak-to-peak) at 632.8 manometers over

the clear circular aperture of the unit under test. Linearity of radiometric measurement shall be

within 5%. Failure to meet the requirements of 3.5.8 shall constitute failure of this test.

4.6 Environmental tests. Environmental testing shall be performed in accordance with the

requirements contained herein, except when a contractor's test plan showing equivalent methods has

been approved by the Government contracting office. When the contractor's test plan deviates from

the test procedures prescribed, the contractor shall be required to show where his own tests and

methods for verifying the specified performance are equivalent. Also, measurements taken by the

contractor during verification testing of all environmental requirements shall be accomplished using

testing apparatus such as an environmental test chamber, vibration test table, pendulum shock device,

or similar equipment for which the technical capabilities to properly simulate extreme climatic or

environmental conditions are scientifically documented. The methods for testing to verify compliance

with all stated performance characteristics selected by the contractor shall be equivalent to the

recommended procedures specified herein.

4.6.1 Temperature shock. Measure compliance with the requirement of 3.6.1. Use of the

tests prescribed in 6.3 is recommended. Failure to meet the requirement shall constitute failure

of the sample.

4.6.2 High temperature. Measure compliance with the requirement of 3.6.2. Use of the

tests prescribed in 6.3 is recommended. Failure to meet the requirement shall constitute failure

of the sample.

4.6.3 Low temperature. Measure compliance with the requirement 3.6.3. Use of the tests

prescribed in 6.3 is recommended. Failure to meet the requirement shall constitute failure of the

sample.