220.127.116.11 Eyepiece and erecting system. This requirement shall be met
when observing through the periscope exit pupil. Luminous transmittance shall
be not less than 60%.
3.10.3 Head assembly. The following requirements shall be met with the
body assembly removed from its mount.
a. Luminous transmittance. Luminous transmittance shall be not less
than 90%. The source of radiance shall be at the exit aperture of the head
assembly and the observation made at the entrance aperture.
b. Resolution. Resolution shall be 2.0 seconds of arc or less when
observing with a telescope of at least 90 power. The entrance pupil of the
telescope shall be not less than 7.0 inches. Resolution shall be as observed
at one focus setting of the telescope.
3.10.4 Resolution - periscope objective system. The requirements of
18.104.22.168 and 22.214.171.124 shall be met with the specified line pairs per milli-
meter positioned at, and projected from the focal plane of the objective sys-
126.96.36.199 On-axis. The objective system shall resolve 2OO line pairs per
millimeter off-axis 0.35 inch.
188.8.131.52 Off-axis 0.35 inch. The objective system shall resolve ZOO line
pairs per millimeter off axis inch.
3.10.5 Objective T number. The requirements of 184.108.40.206 and 220.127.116.11
shall be met with the source of radiance at the focal plane of the objective
system. T number is defined as the F (ratio of focal length to equivalent
diameter) of an idealized circular lens which:
a. Has no obscuration or transmission loss.
b. Has the equivalent focal length of the system in question.
c. Delivers the same irradiance at the focal plane as the system in
18.104.22.168 On-axis. The T number of the objective system shall be not more
than 2.74 as as on-axis.
22.214.171.124 Off-axis 0.35 inch. The T number of the objective system shall
not be more than 3.20 as observed off-axis 0.35 inch.
3.10.6 Resolution - unity power system. Resolution of the unit power
system shall be 1.0 minute or less of arc when observed through any area of
the exit pupil with a 3 power telescope having a 0.50 inch aperture.