Definition of Porro prism in English:

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Porro prism

Pronunciation: /ˈpɒrəʊ/

noun

1A reflecting prism in which the light is reflected on two 45° surfaces and returned parallel to the incoming beam. Compare with roof prism.
Example sentences
  • While not as sexy as a roof prism, the porro prism is a dependable unit made for the outdoors.
  • Two porro prism binocular models are new, the 8x42 mm and the 10x42 mm.
  • Modern roof prism designs are capable of performance just as good as a comparable porro prism design, due to current technology such as phase coating and improved reflective backing materials on the prisms.
1.1 (porro prisms or porro-prism binoculars) A pair of binoculars using two Porro prisms at right angles, resulting in a conventional instrument with objective lenses that are further apart than the eyepieces.

Origin

Named after the Italian scientist Ignazio Porro (1801–75).

For editors and proofreaders

Line breaks: Porro prism

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