pentaprismn.

Brit.

/ˈpɛntəprɪz(ə)m/, U.S.

/ˈpɛn(t)əˌprɪz(ə)m/

Origin: Formed within English, by compounding. Etymons: pentagonal adj., prism n.

Etymology: < penta- (in pentagonal adj.) + prism n.

A prism whose cross-section is a pentagon including one right angle, so that with silvered reflecting surfaces any ray entering the prism through one of the faces forming the right angle is deflected through 90 degrees.

ΘΚΠ

the world > physical sensation > sight and vision > optical instruments > instruments to refract, etc., light > [noun] > prism

prism1612

Nicol prism1838

Foucault prism1882

biprism1884

Fresnel biprism1890

Porro prism1909

pentaprism1937

1937 Magneto-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.

1943 D. 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.

1954 Amateur 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.

1977 J. 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.

1991 Photo Answers June 74/3 When you come to the end of the film, a combination of two buttons on either side of the pentaprism must be pressed to rewind it back into the cassette.

This entry has been updated (OED Third Edition, September 2005; most recently modified version published online March 2022).

单词	pentaprism
释义	pentaprismn. Brit. /ˈpɛntəprɪz(ə)m/, U.S. /ˈpɛn(t)əˌprɪz(ə)m/ Origin: Formed within English, by compounding. Etymons: pentagonal adj., prism n. Etymology: < penta- (in pentagonal adj.) + prism n. A prism whose cross-section is a pentagon including one right angle, so that with silvered reflecting surfaces any ray entering the prism through one of the faces forming the right angle is deflected through 90 degrees. ΘΚΠ the world > physical sensation > sight and vision > optical instruments > instruments to refract, etc., light > [noun] > prism prism1612 Nicol prism1838 Foucault prism1882 biprism1884 Fresnel biprism1890 Porro prism1909 pentaprism1937 1937 Magneto-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. 1943 D. 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. 1954 Amateur 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. 1977 J. 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. 1991 Photo Answers June 74/3 When you come to the end of the film, a combination of two buttons on either side of the pentaprism must be pressed to rewind it back into the cassette. This entry has been updated (OED Third Edition, September 2005; most recently modified version published online March 2022). < n.1937
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