MIL-PRF-49156B
3.4.3.2 Adapter concentricity. The concentricity of the mechanical axis
associated with the 1.551 inch diameter and the mechanical axis associated with
the 1.244 inch diameter shall be as specified on adapter drawing SM-D-804194.
3.4.4 Linear distortion. The linear distortion of the eyepiece assembly
at the edge of the 18 mm format shall be between 7.0 percent and 9.5 percent
pincushion distortion.
3.4.5 Field of view. The field of view of the eyepiece assembly shall be
40 ± 2 for the 18 mm format.
o
3.4.6 Exit pupil versus eye relief. The exit pupil diameter of the
eyepiece assembly shall be no less than 9.8 mm at an eye relief of 15.0 mm ± 0.2
for a zero diopter setting.
3.4.7 Field flatness/field tilt. The field flatness/field tilt shall
deviate no more than ± 1/3 diopter over an 18 mm format with a 40 mm concave
radius of curvature at the zero diopter image plane of the eyepiece assembly.
3.4.8 Transmission. The transmission of the eyepiece assembly shall not
be less than 78 percent over its full aperture for the spectral output of
phosphor type number 10-52 (RCA F2126 or equivalent) (see 3.9.5).
3.4.9 Modulation transfer function (MTF). The MTF values of the eyepiece
assembly shall not be less than those specified in Table I when tested using an
S-11 photomultiplier tube and a green filter (Wratten No. 58 or equivalent over a
2856 K ± 200 tungsten light source) to simulate P-20 illumination in the test
setup.
Table I.
Modulation transfer function.
Orientation & Pupil Location1
Spatial Frequency2
10 lp/mm
20 lp/mm
30 lp/mm
40 lp/mm
on-axis & centered
92%
82%
66%
43%
on-axis & 1 mm decentered
87%
78%
60%
40%
on-axis & 2 mm decentered
81%
62%
42%
23%
on-axis & 4 mm decentered
50%
32%
23%
13%
on-axis & 5 mm decentered
28%
17%
12%
6%
14° off-axis radial & centered
90%
78%
60%
39%
14° off-axis tangential & centered
90%
78%
60%
39%
1
incorporate a 5 mm stop at a 15 mm eye relief
2
in units of line pairs per millimeter (lp/mm)
3.4.10
Weight.
The weight of the cell assembly shall not exceed 65 grams.
3.5 Environmental characteristics. For the purpose of post-environmental
testing, "perform properly" shall be defined as the ability to successfully
complete, in order, the modulation transfer function (3.4.9), transmission
(3.4.8), and flange focal distance (3.4.2) tests.
3.5.1 Vibration. The eyepiece assembly shall not be damaged (see 3.9.1)
by vibration in the frequency range of 10 hertz (Hz) to 55 Hz with a double
amplitude of 0.050 inch ± 0.005.
3
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