untrained eye. You must learn to scan through
practice. Detailed information to help develop
scanning skills is given in Basic Military
Requirements.
Maintenance
To make sure the sights are always ready for
operation, organizational maintenance personnel must
perform a systematic inspection to discover and
correct defects before they result in equipment failure.
Scheduled maintenance is to be performed as
described on current MRCs. If any part is defective or
missing, other than those authorized for replacement
or repair, requisition a replacement sight according to
normal supply procedures.
NIGHT VISION GOGGLES
Night vision goggles, AN/PVS 5A, 5B, and 5C
(fig. 2-18) provide improved night vision, using
available light from the night sky. An auxiliary IR light
source provides illumination for close-up work when
ambient light is low. The goggles enable the user to
observe from the air, as well as perform normal ground
tasks such as reading, walking, and driving.
The goggles are binoculars consisting of two
identical monocular eyepieces mounted on an
adjustable frame and may be moved sideways. Each
monocular assembly consists of three primary
subassemblies: objective lens assembly, image
intensifier, and eyepiece lens assembly. The goggles
are mounted in a cushioned face assembly, which is
strapped on to the user. The goggles are approximately
5 inches high, 7 inches wide, 6 inches deep, and weigh
32 ounces without carrying case.
The mechanical function of the goggles is to
accommodate differences in the physical
characteristics of individual users. This is done by
adjusting the IPD, diopter setting, focus, and eye
relief.
The two monocular assemblies are mounted in the
frame and may be moved laterally to coincide with
individual user’s IPD. Lateral movement is performed
by loosening the lever clamp, which releases tension
from the guide assembly and permits each monocular
eyepiece to slide on flanges of the tube housing. Each
monocular eyepiece is moved manually to the desired
IPD, and the lever clamp is tightened.
Figure 2-18.—AN/PVS 5A, 5B, and 5C night vision goggles.
To adjust the diopter setting, adjust each eyepiece
by rotating the diopter adjust ring, which moves the
eyepiece assembly nearer to or further from the user's
2-17
