188.8.131.52 Cleanliness, head assembly. Perform this test prior to assembl-
ing the body assembly to the mounting plate assembly. The head assembly shall
be visually examined through the entrance window and exit aperture with the
unaided eye. Inspection for moisture shall be made by the technique of sha-
dowing. Inspection for dirt or foreign particles shall be made by viewing a
uniformly illuminated field having a brightness of approximately 300 apparent
foot candles. Cleanliness of the head assembly shall conform to the require-
ments of 184.108.40.206.
220.127.116.11 Cleanliness of unity power system, body assembly. Perform this
test on the body assembly prior to its assembly to the mounting plate assembly.
Position a diffuse light source at the entrance window, then visually inspect
the unity power optical system through the exit window. Then position the
light source at the exit window and visual inspect the optical system through
the entrance window. The unity power system of the body assembly shall con-
form to the requirements of 18.104.22.168.
22.214.171.124 Cleanliness of nine power system, tube installed. Perform this
test with the head assembly and body assembly assembled as a periscope. Pre-
sent diffuse illumination from a 2870 100K tungsten lamp to the en-
trance window of the head assembly. Position the periscope switch in the ON
Position and project the periscope reticle into the optical system. Visually
inspect the nine power system through the periscope eyepiece. The nine power
system shall conform to the requirements of 126.96.36.199a.
188.8.131.52 Cleanliness of nine power system, tube removed. Perform this
test with the head assembly and body assembly assembled as a periscope, and
the image tube removed from the body assembly. Position a diffuse white light
source in the image tube cavity. Visually inspect the objective system through
the head window, then the eyepiece system through the periscope eyepiece. The
nine power system shall conform to the requirements of 184.108.40.206b.
220.127.116.11 Resolution - nine power system, on-axis. Perform this test
using a projected or mechanical target. The effective range shall be not less
than 40 feet. The radiance presented to the periscope shall have a color
temperature of 2870 100K. The background luminance and contrast (high
and low) of the target shall conform to the USAF 1951 Resolution Pattern in
accordance with MIL-STD-150. Adjust the focus of the periscope. The resolu-
tion target shall have the detectable line structure and proper line count
when observed through the eyepiece wih unaided eye. Resolution on-axis for
high and low contrast shall meet the requirements specified in 3.11.3.
The image tube must be erased (completely discharged), and the
observer dark adapted for not less than 15 minutes before performing
the low contrast resolution tests.