MIL-DTL-62478C(AT)
characteristic identification, inspection results, and disposition of lot (accepted or rejected).
Corrective action taken on noted defects shall be subject to approval by the Government.
4.6 Operating requirements verification.
4.6.1 Resolution verification.
4.6.1.1 Optical coupler resolution verification. To determine conformance to 3.3.1.1, the
optical coupler shall be mounted in a test fixture as shown in figure 1. Using the USAF 1951 test
chart or the NBS 1010A microcopy test chart, the high contrast target shall be brought into sharp
focus. The smallest resolved pattern shall be noted and the angle of resolution in the object plane
shall be calculated. An optical magnifier (microscope) may be used to aid in the observation.
The coupler shall clearly resolve an angle of 104 arc seconds, or less, on axis.
4.6.1.2 Integrated system resolution verification. To determine conformance to 3.3.1.2,
the optical coupler, G/VLLD, ITA and collimator shall be mounted onto the alignment fixture as
shown in Figure 2. The high contrast test target shall be brought into sharp focus at the
intersection of the G/VLLD reticle crosshairs, if a G/VLLD is used. An optical magnifier or
dioptometer may be used to aid the observation at the ITA eyepiece. The resolved angle shall be
8 arc seconds or less, on axis, with the observer s eye anywhere within the exit pupil of the ITA
eyepiece. The G/VLLD, if used, shall be electrically connected and the lens cover shall be
closed to prevent firing of the laser. The G/VLLD LED data numbers shall appear as zeros and
shall be clearly resolved, if a G/VLLD is used.
NOTE: Wherever the G/VLLD is referenced in a test, an optical test fixture which is
equivalent to the G/VLLD may be used in its place.
4.6.2 Astigmatism verification. To determine conformance to 3.3.2, the optical coupler
shall be mounted as shown in Figure 1. The image of the astigmatism target shall be brought
into sharp focus. When the image is viewed through an optical magnifier (microscope), readings
shall be made when both the vertical lines of the astigmatism target are in focus and when the
horizontal lines of the astigmatism target are in focus. The astigmatism, in diopters, is the
difference between the two readings. A difference of 0.01 in. (0.254 mm) corresponds to
0.2 diopter. The astigmatism shall not be greater than 0.2 diopter.
4.6.3 Magnification verification. To determine conformance to 3.3.3, install the optical
coupler on the ITA. A telescope coupled to the ITA eyepiece shall be used to bring the target
image into sharp focus at the center of the field. The angular size of the target image shall be
measured using the calibrated reticle of the telescope. The telescope shall then be repositioned to
focus directly on the target and the angular size of the target shall be measured. The
magnification shall be calculated as the ratio of the first to the second angular measurements
taken. The magnification shall be 1 ± 7%.
4.6.4 Entrance pupil verification. To determine conformance to 3.3.4, the integrated
system configuration shall be used. With the G/VLLD pupil matched to the optical coupler, a
10
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business