UA, herein referred to as the Detector-Dewar.

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MIL-PRF-49319A(CR)

maintenance of the vacuum. Each getter shall withstand at least seven (7) firings in operational use.

Activation current (amperes) and time (minutes) shall be provided on the label as shown in View K

on Drawing 80063-A3172178. Data shall be marked in black characters on a light background in

accordance with Note 27 of Drawing 80063-A3172178.

3.5 Performance characteristics.

3.5.1 Detector-Dewar defects. The Detector-Dewar shall operate at 80�, +5/-20�K. The

Detector-Dewar shall contain no more than two (2) defective elements, as defined in 3.12.2. The

center twelve (12) elements shall be defect-free. Defects shall be separated from one another by at

least four (4) nondefective elements. Elements which are open (dead) or have a D*BB or less than

7.0 x 10 9 shall be electrically strapped to an adjacent element with common ground (perform 4.5.1

for acceptance).

3.5.2 Time constant. The time constant is the time for the element response to reach 63% of

its steady state value when irradiated by a 7.5-12 micrometer source producing a signal to noise

ratio of <100:1. The time constant of each Detector-Dewar element shall be less than 2

microseconds (perform 4.4.2 for acceptance).

3.5.3 Sensitive area. The physical area shall be 0.0960 by 0.0144 inches or greater. Perform

4.4.3 for acceptance.

3.5.4 Crosstalk. The crosstalk signal level between any 2 elements shall be less than

-26 dB as determined by measuring 4 elements. Perform 4.4.4 for acceptance.

3.5.5 Blackbody detectivity. The blackbody detectivity of all nondefective elements shall not

be less than 10.5 x 109 cm Hz � w-1 , except for channels 85-96, which shall not be less than 11.5 x

109 cm Hz � w-1 when the Detector-Dewar is cooled with LN2 to 77 �3�K (perform 4.4.5 for

acceptance). Noise measurements shall be made on each element of the array under the following

conditions: The Detector-Dewar cooled to 77 �3�K with LN2, 295, �5�K background temperature

and equivalent noise bandwidth of 9 KHz �200 Hz with low frequency 3 dB point (high pass) no

greater than 80 Hz. Using the results of these measurements, the results of 500�K blackbody

responsivity measurements and the nominal detector element size (see 3.12.7), the 500�K blackbody

detectivity for each element of the array shall be calculated.

3.5.5.1 Noise. The detector noise of each element shall be at least 2.5x10-9 volts rms Hz1/2.

3.5.6 Detector Resistance. The detector resistance of each element shall be not less than 20

ohms and not greater than 150 ohms.

3.5.7 Responsivity. The average 500�K blackbody responsivity of the acceptable elements

shall not be less than 10.3 x 103 volts/watt, nor greater than 20 x10 3 volts/watt, when the Detector-

Dewar is cooled with LN2 to 77 , �3�K. The blackbody responsivity of each element shall not vary

by more than �20 percent of the mean value of the elements which are not defective. Nominal