MIL-PRF-49446B(CR)
3.5.9 Spectral response. Each element of the Detector-Dewar shall have special
sensitivity, defined as the 50 percent relative response points, of 7.7, ±0.3 to 11.7, ±0.5
micrometers. Perform 4.5.9 for acceptance.
3.5.10 Detector bias. The average bias current of the array shall not exceed 3.0
milliamperes per element, and no one element shall take a bias current of more than 4.0
milliamperes. The total bias power dissipated by the array shall not exceed 30 milliwatts. The
detector element shall be biased with current flow in the same direction. The detector bias pack
shall be operated at + 3.0V+/0,2Vdc. Perform 4.5.10 for acceptance.
3.5.11 Dewar warm and cold shields. The incorporation of an internal cold shield is
optional. If incorporated, the Detector-Dewar shall meet the following Field Of View (FOV)
requirements: The minimum half angle FOV from the center of the end elements of the array in
the elevating direction shall be 14 degrees. In the direction perpendicular to the array's axis, the
cold shield(s) shall allow for each element, no vignetting of any ray to any point on the detector
surface within an angle of 17 degrees. This shall be measured from and on either side of a line
perpendicular to the array's axis and parallel to the optical axis. Perform 4.5.11 for acceptance.
3.5.12 Heat load. The detector heat load shall not exceed 120 milliwatts when all
detector elements are operating at their final bias current and the Dewar is cooled to 80o, ±5 K.
3.5.13 Vacuum integrity. The Dewar shall comply with heat load requirements of 3.5.12
for a period of at least 0ne (1) year. Perform 4.5.13 for acceptance.
3.5.14 Microphonics. When cooled to a temperature of 60-80 K, with full operating
bias applied in accordance with paragraph 3.5.10, and vibrated in accordance with paragraph
3.5.14.1, all elements of the Detector-Dewar shall have no noise peaks above the white noise
reference value greater than 8dB from 300 to 10,000 Hz, and 12dB from 10,001 to 20,000 Hz.
Perform 4.5.14 and 4.5.14.1 for acceptance.
3.5.14.1 Microphonics vibration. The Detector-Dewar shall be coupled to a mechanical
cryogenic refrigerator that produces random vibrational excitation of the Detector-Dewar in three
mutually perpendicular axes. The frequency distribution of the vibrations shall be in a range
from 0 to 20,000 Hz. The RMS sum of the three axis vibration shall be at least of 1.0 g rms.
Each axis shall produce a minimum vibrational excitation of 0.4 g rms. In the frequency range of
2,000 to 20,000 Hz, the RMS sum shall be at least 0.8 g rms. Perform 4.5.14.1 for acceptance.
3.5.15 Apparent thermal mass (cooldown). When mated to a cryogenic cooler capable of
cooling a test mass of 1.25 grams (250 joules) of aluminium (Figure 3) from ambient (296 K) to
80 K in not less than 5, nor greater than 6 minutes, the Dewar cooldown time from ambient
temperature to 80°K shall not exceed the time achieved with the test mass.
3.6 Environmental conditions.
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