|
| |
TM 9-254
9-9.
Coating Optical Components - Continued
e.
The Coating Unit (fig. 9-30). This is a high vacuum machine that must have the capabilities of evaporating
magnesium fluoride and be able to produce a vacuum of 5 x 105 mm of mercury. Refer to the manufactures manual for
the proper maintenance and operating procedure of the vacuum unit.
f.
Coating Procedures (fig. 9-30). The following is a procedure for coating lenses in a high vacuum coating unit.
CAUTION
Before attempting to raise bell jar, all vacuum must be released from system. Failure to release
vacuum will damage bell jar.
(1)
Open SYS VENT valve (17) to release vacuum from bell jar (1).
(2)
Place MAIN PWR switch (15) and AUX PWR switch (10) to the ON position.
CAUTION
Do not attempt to change position of the hoist switch while raising or lowering the bell jar.
Changing the position of the hoist switch while bell jar is in motion will damage the hoist.
(3)
Raise bell jar by setting the HOIST switch (22) to the UP position.
NOTE
Steps (4) through (7) refer to figure 9-31.
(4)
Place holding fixture (fig. 9-29) on support ring (4). Position holding fixture cover (2) on support ring (4).
(5)
Fill crucible (7), level full, with magnesium fluoride and position on turntable (6).
CAUTION
Do not allow filament to come in contact with the magnesium fluoride. This will prevent spattering
which will cause damage to the lens components.
(6)
Adjust turntable (6) to position crucible (7) 1/8 inch from filament (8). Position spatter shield lever (21,
fig. 9-30) to the right.
(7)
Remove dust and dirt from baseplate (5) and turntable (6) with a watchmaker’s blower.
Change 2 9-28
|
