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Parallelism of reticle and image |
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|  MIL-T-46324D(MU)
4.6.4 Cleanliness. - The optical surfaces of the telescope shall be
inspected for cleanliness in accordance with MIL-O-13830. Inspection for
dirt particles shall be made through the eyepiece by viewing a uniformly
illuminated field having a brightness of approximately 300 foot candles.
All dirt size evaluations shall take into account the viewing magnification.
Inspection for condensates shall be made with the unaided eye viewing
through the objective and eyepiece ends of the telescope by the shadowing
technique. Cleanliness shall conform to the requirements of 3.5.4.
4.6.5 Resolution. - Position the telescope on a holding device capable
of accepting the exterior mounting surface of the objective tube of the
telescope. Perform this test utilizing an observation telescope with a
magnification of at least 3 power (3X) and a resolving power chart on a wall
target. The test methods and procedures shall be in compliance with the
"Resolution Test" specified in MIL-0-13830 and the resolving power chart
shall contain 4 line sets as shown in Figure 1 therein. The focus of the
observation telescope shall be established at one best focus setting for
viewing of the detectable line structure and proper line count of the resolu-
tion target. Resolution of the telescope optical system shall meet the re-
quirements specified in 3.6.3.
4.6.6 Accuracy. - Perform the following tests with the telescope
positioned on special testing equipment conforming to 4.5.2.3.1.
4.6.6.1 Collimationn. - Position the telescope with the eyepiece in a
vertical position. Observe through the eyepiece of the telescope. The
intersecting point of the telescope reticle centerlines shall be in coinci-
dence with respect to the intersecting point of the target reticle lines
within the tolerance specified in 3.6.1 as measured on the 0.50 mil diameter
circle of the target reticle. Repeat the collimation test procedure above
when the telescope is rotated 90 to the left and 90 to the right of the
original test position. The intersecting point of the telescope reticle
shall be within the 0.50 mil diameter circle of the target reticle at both
positions to insure overall compliance with 3.6.1.
4.6.6.2 Parallax. - Parallax requirements shall be met when the target
image is adjusted as specified in 3.6.2. Parallax-will be recognized by any
apparent displacement of the telescope reticle lines with respect to the
center target image lines when the observer's head is moved from side to side
or up and down. Parallax shall be measured at the optical axis (center of
the reticle pattern). Displacement between the. telescope reticle and target
image shall not exceed the tolerance specified in 3.6.2.
4.6.6.3 Parallelism of reticle and image. - Perform this test in con-
junction with the test in 4.6.1.1 when each of the indices as specified in
3.6.4 are in position and coincident with respect to the index of the "V"
block. One extremity of the telescope vertical reticle shall be coincident
to the vertical target imabe line. The reticle line shall be parallel to
the target image line within the tolerance specified in 3.6.4, as measured at
the other extremity of the telescope reticle line with respect to the target
image tolerance marks.
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