MIL-DTL-62420B(AT)
4.10.1 Temperature.
4.10.1.1 Low temperature. The periscope shall be placed in a temperature chamber and
subjected to the low temperature test as specified in MIL-STD-810, method 502.3, procedure I.
A temperature of -65 degrees Fahrenheit (°F) (-54 degrees Celsius (°C)) shall be maintained for a
period of 24 hours. At the conclusion of this time, the unit shall be returned to 73 +18°F
(23 +8°C). The unit shall show no indication of moisture buildup, bond separation or other forms
of image degradation and shall meet the requirements of 3.7.1.3. The periscope shall then be
subjected to and pass the tests specified in 4.7.1.1, 4.7.1.4, 4.7.1.5 and 4.10.6.
4.10.1.2 High temperature. The periscope shall be exposed to three 24 hour cycles of the
hot, dry temperature profile as given in table II. Relative humidity shall be not greater than 10%
during exposure. After exposure to the temperature profile but prior to testing for light
transmission, resolution and submergence, the unit shall be at a minimum of 160°F (71°C) and
shall show no indication of moisture buildup, bond separation, or other forms of image
degradation and shall meet the requirements of 3.7.1.3. The periscope shall then be returned to
normal ambient temperature and pass the tests specified in 4.7.1.1, 4.7.1.4, 4.7.1.5 and 4.10.6.
4.10.1.3 Mirror and window laminations. The laminations of the mirrors and windows
shall be visually inspected in accordance with 4.7.1 for compliance with 3.7.1.3. The appearance
of any bubbles, blisters, cracks or separations exceeding the limitations of 3.6.1 in the clearance
aperature shall be considered evidence of bond failure.
4.10.2 Humidity. The periscope shall be exposed to two 24 hour cycles of the humidity
profile given in table IV. Prior to the test, the unit shall be conditioned at 100°F (38°C) and 50%
maximum relative humidity for 24 hours. After the test, the unit shall be conditioned at 73°F and
50% maximum relative humidity for 24 hours. After exposure, the unit shall exhibit no indication
of moisture buildup, bond separation, or other forms of image degradation. The periscope shall
then be subjected to and pass the tests specified in 4.7.1.1, 4.7.1.4, 4.7.1.5, and 4.10.6.
4.10.3 Salt fog. The periscope shall be tested in accordance with the salt fog test
described in Method 509.3, Procedure 1 of MIL-STD-810. Subsequently, the periscope shall be
subjected to and pass the tests in accordance with 4.7.1.1, 4.7.1, 4.7.1.5, and 4.10.6 and checked
for any delaminations or physical damage.
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