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TM 9-254
9-9.
Coating Optical Components - Continued
NOTE
Coating is a thin film of magnesium fluoride applied to the surface of optical elements at a
thickness of one-quarter wavelength of light (550 to 600 millimicrons).
b.
Identifying Coated Optics. To identify coated optical elements, hold the element at an angle to a light source.
Observe the reflection of the light source on the surface of the lens. The reflection of the light will have a purplish or
bluish-purple tint if the element is coated properly.
c.
Preparation for Coating. The procedure for cleaning optical elements is as follows:
(1)
Mix a solution of 1/2 teaspoon of Duponol Me Dry and 1 quart of luke-warm water in a stainless steel
tray. Place a pad of cheesecloth in the bottom of the tray to protect element surfaces.
(2)
Carefully place lens elements in the tray and allow to soak from 1 to 2 minutes. Then wash each lens
element with a piece of cheesecloth in the cleaning solution.
(3)
Remove one element at a time and dry the element with a piece of cheesecloth (fig. 9-28). Inspect
element for foreign matter such as dirt and lint. If the element is not clean repeat steps (1) through (3)
above.
(4)
Place clean lens elements on holding fixture as described in paragraph d.
Figure 9-28. Proper Method of Holding a Lens
d.
Holding Fixture Setup (fig. 9-29). The holding fixture is designed with adjustable rails to hold any size or
shape of optical element. The procedure for setting up the fixture is as follows:
Change 2 9-26
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