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- Porro_prism abstract "In optics, a Porro prism, named for its inventor Ignazio Porro, is a type of reflection prism used in optical instruments to alter the orientation of an image.It consists of a block of glass shaped as a right geometric prism with right-angled triangular end faces. In operation, light enters the large rectangular face of the prism, undergoes total internal reflection twice from the sloped faces, and exits again through the large rectangular face. Because the light exits and enters the glass only at normal incidence, the prism is not dispersive.An image travelling through a Porro prism is rotated by 180° and exits in the opposite direction offset from its entrance point. Since the image is reflected twice, the handedness of the image is unchanged.Porro prisms are most often used in pairs, forming a double Porro prism. A second prism, rotated 90° with respect to the first, is placed such that the beam will traverse both prisms. The net effect of the prism system is a beam parallel to but displaced from its original direction, with the image rotated 180°. As before, the handedness of the image is unchanged. Double Porro prism systems are used in small optical telescopes to re-orient an inverted image (an arrangement is known as a image erection system), and especially in many binoculars where they both erect the image and provide a longer, folded distance between the objective lenses and the eyepieces.Commonly, the two components of the double Porro system are cemented together, and the prisms may be truncated to save weight and size.While a single porro prism can be constructed to work as well as a roof prism, it is seldom used as a such. Therefore to reduce the cost of production for a porro prism, the edge of the roof is usually left out. Sometimes only one small window as entrance surface and one window as exit surface are polished. The distinction between a roof prism and a porro prism is that for the roof prism the roof edge lies in the same plane as entrance and exit beam, while for a porro prism the (left out) roof edge is orthogonal to the plane formed by the beams. Furthermore, the roof prism has no displacement and a deviation typically between 45° and 90°, while in a single porro prism the beam is typically deviated by 180° and displaced by a distance of at least one beam diameter.A variation on the double Porro prism is the Porro-Abbe prism.".
- Porro_prism thumbnail Visszatükrözés_prizmán_2.jpg?width=300.
- Porro_prism wikiPageExternalLink roof-porro.html.
- Porro_prism wikiPageID "531592".
- Porro_prism wikiPageRevisionID "543768749".
- Porro_prism hasPhotoCollection Porro_prism.
- Porro_prism subject Category:Italian_inventions.
- Porro_prism subject Category:Prisms.
- Porro_prism type Ability105616246.
- Porro_prism type Abstraction100002137.
- Porro_prism type Attribute100024264.
- Porro_prism type Cognition100023271.
- Porro_prism type Creativity105624700.
- Porro_prism type Invention105633385.
- Porro_prism type ItalianInventions.
- Porro_prism type Polyhedron113883885.
- Porro_prism type Prism113884511.
- Porro_prism type Prisms.
- Porro_prism type PsychologicalFeature100023100.
- Porro_prism type Shape100027807.
- Porro_prism type Solid113860793.
- Porro_prism comment "In optics, a Porro prism, named for its inventor Ignazio Porro, is a type of reflection prism used in optical instruments to alter the orientation of an image.It consists of a block of glass shaped as a right geometric prism with right-angled triangular end faces. In operation, light enters the large rectangular face of the prism, undergoes total internal reflection twice from the sloped faces, and exits again through the large rectangular face.".
- Porro_prism label "Porro prism".
- Porro_prism label "Porroprisma".
- Porro_prism label "Porroprisma".
- Porro_prism label "Prisma de Porro".
- Porro_prism label "Prisma di Porro".
- Porro_prism label "Redresseur terrestre".
- Porro_prism label "Призма Порро".
- Porro_prism label "普羅稜鏡".
- Porro_prism sameAs Porroprisma.
- Porro_prism sameAs Prisma_de_Porro.
- Porro_prism sameAs Redresseur_terrestre.
- Porro_prism sameAs Prisma_di_Porro.
- Porro_prism sameAs Porroprisma.
- Porro_prism sameAs m.02m758.
- Porro_prism sameAs Q1898382.
- Porro_prism sameAs Q1898382.
- Porro_prism sameAs Porro_prism.
- Porro_prism wasDerivedFrom Porro_prism?oldid=543768749.
- Porro_prism depiction Visszatükrözés_prizmán_2.jpg.
- Porro_prism isPrimaryTopicOf Porro_prism.
