Porro prismn.

Brit.

/ˈpɒrəʊ ˌprɪz(ə)m/, U.S.

/ˈpɔroʊ ˌprɪz(ə)m/,

/ˈpɑroʊ ˌprɪz(ə)m/

Forms: also with lower-case initial.

Origin: From a proper name, combined with an English element. Etymons: proper name Porro , prism n.

Etymology: < the name of Paolo Ignazio Pietro Porro (1801–1875), Italian geodesist and optical engineer, who first used such prisms in the construction of optical instruments + prism n.

Optics.

A reflecting prism in which light enters through the hypotenuse and is reflected successively at each of the other two faces, used in optical instruments, esp. binoculars and telescopes, to alter the orientation of images.Porro prisms are typically used in pairs, with the second prism at right angles to the first. Each prism rotates and displaces the image, and the combined effect of the two is a displaced image rotated 180 degrees in its own plane.

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

1909 Science 10 Sept. 344 Among the most important of these are the Zeiss stereo-binocular field glasses with Porro prisms, which are now the standards of excellence in this branch of applied optics.

1945 Sci. Monthly Sept. p. i. (advt.) Porro prism set from army's 6 power binocular.

1983 Outdoor Life Aug. 44 Lately there's been a great demand for roof prism binoculars because generally the design has been used to produce glasses that are slightly more compact than those using the porro prism design.

2002 Outdoor Photographer Oct. 80/1 Porro-prisms are a little bulkier [than roof-prisms] and have the familiar dogleg shape that allows for simpler optical arrangements.

This is a new entry (OED Third Edition, December 2006; most recently modified version published online March 2022).

单词	porro prism
释义	Porro prismn. Brit. /ˈpɒrəʊ ˌprɪz(ə)m/, U.S. /ˈpɔroʊ ˌprɪz(ə)m/, /ˈpɑroʊ ˌprɪz(ə)m/ Forms: also with lower-case initial. Origin: From a proper name, combined with an English element. Etymons: proper name Porro , prism n. Etymology: < the name of Paolo Ignazio Pietro Porro (1801–1875), Italian geodesist and optical engineer, who first used such prisms in the construction of optical instruments + prism n. Optics. A reflecting prism in which light enters through the hypotenuse and is reflected successively at each of the other two faces, used in optical instruments, esp. binoculars and telescopes, to alter the orientation of images.Porro prisms are typically used in pairs, with the second prism at right angles to the first. Each prism rotates and displaces the image, and the combined effect of the two is a displaced image rotated 180 degrees in its own plane. 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 1909 Science 10 Sept. 344 Among the most important of these are the Zeiss stereo-binocular field glasses with Porro prisms, which are now the standards of excellence in this branch of applied optics. 1945 Sci. Monthly Sept. p. i. (advt.) Porro prism set from army's 6 power binocular. 1983 Outdoor Life Aug. 44 Lately there's been a great demand for roof prism binoculars because generally the design has been used to produce glasses that are slightly more compact than those using the porro prism design. 2002 Outdoor Photographer Oct. 80/1 Porro-prisms are a little bulkier [than roof-prisms] and have the familiar dogleg shape that allows for simpler optical arrangements. This is a new entry (OED Third Edition, December 2006; most recently modified version published online March 2022). < n.1909
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