MIL-PRF-49319A(CR)
detector element size shall be used in responsivity calculations and blackbody temperature shall be
500 , ±5°K (see 3.12.7).
3.5.8 Temperature sensors. At least two calibrated 2N2222 temperature sensor chips shall be
installed at or near the detector array location in the Dewar to provide an electrical signal which is
an analog of temperature. The temperature sensor shall have a junction voltage of 1.060, 0.015
volts with a 1.00, 0.01 milliamperes (mA) forward current when the Detector-Dewar is operated at
77 , ±3 K. The voltage shall be recorded on the appropriate label on the Detector. The 77 K
calibration point shall be determined by cooling the inner Dewar with LN2. A 1.00, ±0.01 mA bias
shall be applied to the sensor diode and the voltage shall be monitored and recorded at the 77 K
calibration point.
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. The
spectral response of the sixth element from each of the array or adjacent element on the high end
and the higher number of the two center elements shall be tested per "Standard Procedures for
Testing Infrared Detectors and Describing Their Performance", by R.C. Jones, D. Goodwin, and G.
Pullen, dated 12 September 1960, Office of the Director of Defense Research and Engineering. If
these elements are defective an adjacent element may be substituted.
3.5.10 Detector bias. The average bias current of the array shall not exceed 3.0 mA per
element, and no one element shall take a bias current of more than 4.0 mA. The detector bias power
shall be tested as per 3.5.9, above. The total bias power dissipated by the array shall not exceed 30
milliwatts (mW). The detector element shall be biased with current flow in the same direction. The
detector bias pack shall be operated at 3.0, ±0.2 Vdc.
3.5.11 Detector-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. During in-process inspection, the
warm and cold shields shall be measured to ensure conformance with the requirement. Alignment
of the cold shield relative to detector elements shall be checked 100 percent during in-process
inspection.
3.5.12 Heat load. The detector heat load shall not exceed 120 mW when all detector
elements are operating at their final bias current and the Detector-Dewar is cooled to 80 , ±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 one (1) year.
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,
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