An Amici roof prism, named for its inventor, the Italian

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

Giovanni Battista Amici Giovanni Battista Amici (; 25 March 1786 – 10 April 1863) was an Italian astronomer, microscopist, and botanist. Amici was born in Modena, in present-day Italy. After studying at Bologna, he became professor of mathematics at Modena, and in 183 ...

, is a type of reflecting

prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...

used to deviate a beam of light by 90° while simultaneously inverting the image. It is commonly used in the eyepieces of

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

s as an image erecting system. It is sometimes called an Amici prism or right angle roof prism. The non- dispersive Amici roof prism should not be confused with the dispersive

Amici prism An Amici prism, named for the astronomer Giovanni Battista Amici, is a type of compound dispersive prism used in spectrometers. The Amici prism consists of two triangular prisms in contact, with the first typically being made from a medium-di ...

. The device is shaped like a standard right-angled prism with an additional "

roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...

" section (consisting of two faces meeting at a 90° angle) on the longest side.

Total internal reflection Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected b ...

from the roof section flips the image laterally. The

handedness In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more Fine motor skill, dextrous. The other hand, comparatively often the weaker, less dextrous or sim ...

of the image is unchanged. The roof faces of the prism are sometimes

coated A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Powder ...

to provide

mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...

surfaces. This allows the prism to be constructed with other beam deviate angles besides 90° without being limited by total internal reflection.

References

Prisms (optics) Italian inventions {{optics-stub

See also

References