Photonics Dictionary: R

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radioactive tracer

A radioactive element that is placed or injected into a system to obtain an autoradiogram of the system. It is used in a number of fields where standard methods of internal imaging, for example,...

radix

Total number of characters available to each position of a digital numeric system.

rail -> optical bench

A support for optical parts comprising a solid bed that permits precise longitudinal movement of one component relative to the others, and a number of sliders equipped with holders for lenses, lamps,...

regenerative amplifier

A type of multiple-pass amplifier in which no optical leakage is allowed until a finite number of passes has occurred; at this time the entire cavity output is released as one pulse.

relative aperture

The ratio of the diameter of the entrance pupil in an optical system to the equivalent focal length of that system. The relative aperture is denoted as a fraction in which f, the equivalent focal...

relative brightness

A figure of merit corresponding to the amount of light seen by a viewer through binoculars. A higher number indicates a brighter image in low-light situations. The relative brightness value is...

replicated optics

Optical components, usually reflectors, produced using proprietary techniques that transfer the precision of a master to a number of elements.

resolution chart -> resolution target

A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the limiting number of lines per millimeter that an optical system is capable of...

resolution target

resolution test chart -> resolution target

resolving power chart -> resolution target

responsive quantum efficiency

The number of electrons emitted per photon incident upon a photodetector.

Rockwell hardness

Rockwell hardness (Rc) refers to a method for measuring the hardness of a material, primarily metals, using an indentation test. It is named after the Rockwell scale, which was developed by Stanley...

Rydberg atom

The term "Rydberg atom" refers to an atom in a highly excited state where one or more of its electrons are in a Rydberg orbital. A Rydberg atom is characterized by having an electron orbit that is...

Photonics DictionaryR

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