tank periscope

tank periscope

[′taŋk ¦per·ə‚skōp]
(optics)
A periscope permitting a tank occupant to observe without being exposed to bullet fire; employs a pair of plane, parallel, reflecting surfaces (either mirrors or prisms) so arranged in a mount that the path of light through the instrument forms a letter Z.
References in periodicals archive ?
Jones alludes to the fact that Major Steele's follow-on report, dealing with tank periscopes, was "labeled top secret" and that "because it was handled quietly, and was a classified matter, the internal affair has .