MIL-PRF-49052G
3.6.19 Photocathode, microchannel plate, and screen quality. When the
screen is viewed with a 10X or greater magnifier, with no light, then with 2 x
10-6 fc incident on the photocathode, there shall be no bright spots. There also
shall be no discernible field emission (see 3.12.13) brighter or larger than the
background scintillation (see 3.12.14) noise. When the screen is viewed with a
10X or greater magnifier and with the radiation level on the photocathode
adjusted to obtain best spot contrast, the opaque or dark spots which exceed a
contrast of 30 percent of their surrounding area shall not exceed the size and
quantities specified in Table IV. The size of noncircular spots shall be
determined on the basis of area equal to circular spots. When the distance
between two spots is less than the maximum dimensions of either spot, the two
spots shall be considered as one spot with a size equal to the sum of the maximum
dimensions of the two spots plus the amount of separation between them.
Graininess caused by a grainy or "peppery" phosphor screen, channel-to-channel
gain variations, or fiber-to-fiber transmission variations shall not be
discernible over the useful diameter to the degree that it detracts from normal
operation, when viewed with a 10X or greater magnifier and with the photocathode
uniformly illuminated. Due to the subjectivity of these measurements,
disagreement concerning compliance shall be resolved by performing a resolution
test in the disputed area, measured at an input illumination of not greater than
1 x 10-4 fc incident to the photocathode. If the assembly passes the minimum
resolution test in compliance with 3.6.15 and/or the visual requirements stated
above, the assembly shall be accepted.
Table IV.
Assembly dark spots.
Number of spots
Number of spots within
Size of spot in
Number of spots
within an annulus
an annulus bounded by
inches
within a 0.22 inch
bounded by two
two circles, 0.58 inch
diameter circle
circles, 0.22 inch in diameter and the
and 0.58 inch in
total screen diameter
diameter
.015
<
size
0
0
0
size ≤ .015
.012
<
0
1
2
size ≤ .012
.009
<
0
3
6
size ≤ .009
.006
<
1
6
10
size ≤ .006
.003
<
1
15
20
size ≤ .003
disregard
disregard
disregard
Note:
The 0.22 inch and 0.58 inch circles on the image screen shall be concentric
and their centers shall be coincident with the optical axis of the assembly.
3.6.20 Phosphor decay. With an input illumination of 1 x 10-5 fc to 5 x 10-5
fc, the decay due to the output phosphor screen response shall be within the
limits specified in 3.12.2 at 10 milliseconds, 100 milliseconds, 500
milliseconds, and 1 second from the start of decay.
9
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business