C1, TM 9-1240-318-35
length of range line when viewing a test target or
observed in a dark area.
standard collimator reticle. For telescope XM134 (reticle
pattern rotated 90 degrees counterclockwise from that of
3-18. Vibration Test. (Depot Maintenance Only)
telescope M120) the interrupted range line, located
nearest the geometric axis of the reticle pattern (800
With the mount telescope M148 or mount telescope
meter range line), shall be parallel within 2.0 degrees of
XM164 secured on the universal vibration tester (fig. 2-1)
arc to the image of a target line perpendicular to the
and telescope M120 or telescope XM134 secured to its
horizontal plane of the dovetail, or 1.4 mils over entire
respective mount, vibrate for 15 seconds at an amplitude
length of range line.
of 1/16-inch (1/8-inch total movement) and at a
frequency of 30 cps. There shall be no evidence of
3-16. Reticle Accuracy
physical failure, such as glass breakage, loosening of
parts, and binding or sealing.
The optical elements in the assembled telescope will be
so adjusted that the angular value between the
boresighting cross and the 2000 meter range line of the
telescope shall be 18.6 mils, +0.6 mil for telescope M120
Check that all screws, cells, and retaining rings are
and 36.95 mils +0.6 mil for telescope XM134 when
checked against a testing target or collimator reticle
having an accurately graduated angular scale.
3-20. Purging and Charging. (Depot Maintenance
Check that telescope has been purged and charged and
With instrument light; M52E1 or an equivalent properly
that no leaks are present.
mounted, the reticle will appear clearly defined when