| 释义 |
pentaprism|ˈpɛntəprɪz(ə)m|
Also penta prism, penta-prism.
[f. pentagonal a. (n.) + prism.]
A prism whose cross-section is a pentagon with one right angle and three angles of 112½°, so that with silvered reflecting surfaces any ray entering it through one of the faces forming the right angle is deflected through 90°.
1937Magneto-theodolite (Ordnance Survey) 5 The telescope is eccentrically mounted and the change over from theodolite generation to magnetometer operation..takes place in one second by throwing into the line of sight inside the telescope tube a penta-prism which reflects through 270° rays from the illuminated diaphragm of the eyepiece. 1943D. H. Jacobs Fund. Optical Engin. xi. 160 The penta prism..makes possible the modern high-precision rangefinder. This prism has the unique property of deviating a beam exactly 90° in the plane of the rays shown..even if the beam should not strike the end faces exactly normal. 1954Amat. Photographer 19 May 628/2 The Rectaflex is..a..miniature of the eye-level reflex type, the camera having a manually raised 45-deg. mirror..and brilliant-type screen viewed via a pentaprism. 1977J. Hedgecoe Photographer's Handbk. 11 During the past twenty years..the dominant design trend has been the single lens reflex. This includes both the universally popular 35 mm pentaprism types and roll-film versions. |