UA.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12

MIL-PRF-49384B(CR)

This element of inspection shall encompass all visual examinations and dimensional

measurements. Noncompliance with any specified requirements or presence of one or more

defects preventing or lessening maximum efficiency shall constitute cause for rejection.

4.5 Methods of inspection.

4.5.1 Effective Focal Length (EFL). EFL measurements are defined by ANSI PH 3.35,

paragraph 4. Failure to meet the requirements of 3.5.1 shall constitute failure of this test.

4.5.2 f/number. f/number measurements are defined by ANSI PH 3.29, paragraph 2.6.

Also, see paragraph 6.2.i for additional testing information pertaining to f/number. Failure to

meet the requirements of 3.5.2 shall constitute failure of this test.

4.5.3 Linear distortion. Linear distortion is defined by Method 27 or 28 per the document

noted in paragraph 6.2.i. Failure to meet the requirements of 3.5.3 shall constitute failure of this

test.

4.5.4 Modular transfer function (MTF). The MTF of the Imager shall be measured using a

test set calibrated to provide frequency and modules. The MTF shall be measured either

continuously or in 10 discrete steps from 0 to 20 cycles per millimeter (cy/mm). The MTF test

shall be run at infinite conjugates. On-axis MTF shall be measured in a single orientation and

shall not be less than the MTF in figure 1. Off-axis radial MTF shall be measured in the same

plane used for the on-axis image parallel to the plane defined by the flange surface A of figure 3.

The off-axis MTF shall be measured at 2 points in the field 90 degrees apart. The MTF tests

shall be performed using the nominal flange focal distance (see 3.6.6) using the aperture stop

shown in figure 3. Failure to meet requirements of 3.6.4 shall constitute failure of this test.

4.5.5 Relative illumination (RI). Relative illumination shall be measured in accordance

with Method 8 of the document noted in paragraph 6.2.i modified for the spectral region of

interest. Relative illumination shall be measured in 2 mutually perpendicular planes with the

first plane measured across the greatest distance of the oval shape of the mirror. Failure to meet

requirements of 3.5.5 shall constitute failure of this test.

4.5.6 Flange focal distance (FD). Flange focal distance shall be measured from surface A

in figure 2 to the flat-field plane of best MTF (see 3.6.4). Failure to meet requirements of 3.5.6

shall constitute failure of this test.

4.5.7 Field of view. The field of view of the Imager shall be measured as part of the

relative illumination test given in 4.5.5. Failure to meet the requirements of 3.5.7 shall constitute

failure of this test.

4.5.8 Optical transmittance. Optical transmission shall be measured in the 7.6- to 11.75-

micrometer spectral region referenced in the document listed in 6.2.i. Failure to meet

requirements of 3.5.8 shall constitute failure of this test.