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TM 9-254
9-10.
Cementing Optical Components - Continued
(5)
Using a cork stopper, move the top convex element in a slight circular motion to remove any air bubbles
that may have formed in the cement. This also removes excess cement from between the lens
elements.
(6)
Remove excess cement by wiping the edge of the lens elements with a piece of batiste cloth dampened
with acetone.
CAUTION
Position a piece of plate glass over the top of the surface plate to prevent the lens elements from
becoming scratched during the alinement process.
NOTE
The surface plate and plate glass covering used in step (7) below, must be leveled to prevent the
lens elements from shifting during the alinement process.
(7)
Position the lens elements on top of a leveled surface plate.
(8)
Aline the lens elements by positioning two V-blocks, the open jaws of the V-blocks facing each other,
against the outer edges of the lens elements.
(9)
Using the V-blocks, apply a slight pressure to the edge of the lens elements to aline the edges flush with
each other.
CAUTION
Keep oven doors closed during the baking process to prevent the lenses from being exposed to
cool air which could cause separation of the lens elements.
NOTE
o Allow cement to harden for a period of 3 to 5 hours before attempting to move the lens
elements.
o Baking oven must be level to prevent any shifting of the two lens elements.
(10) Remove the glass plate with lenses from the surface plate and place in the baking oven. Bake lenses at
a temperature of 170 to 180 degrees Fahrenheit for a period of 4 to 6 hours. When baking time is
completed, turn oven off and allow lenses to cool slowly to room temperature.
(11) After lenses have cooled, remove them from the oven and clean off any excess cement from edge of the
lens with a sharp knife or razor blade.
(12) Thoroughly clean lens to remove all cement residue, dirt, and lint.
(13) Inspect for any defects resulting from the cementing process, such as dirt, lint, separation, or air bubbles
between the lenses. Any lens having defects and not meeting the inspection requirements of paragraph
9-6 will have to be separated and recemented.
9-35/(9-36 blank)
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