Photonics Dictionary: C

The radiation produced when a charged particle traverses a medium that has a refractive index considerably greater than unity. The moving particle has a velocity that exceeds the velocity of light in...

Radiation in which the phase relationship between any two points in the radiation field has a constant difference, or is exactly the same in either the spatial or the temporal mode throughout the...

Category inclusive of all radiation that is incited electronically, except laser radiation, as a function of the application of laser power to a system.

Radiation in which every ray from any given object point can be considered to be parallel to every other. This is never completely the case: The light from a star is really diverging, and all...

A mercury vapor discharge lamp that has cadmium added to emit radiation in the red region as a complement to the mercury vapor's blue and green radiation.

The three lines in the spectrum of cadmium that have the purest radiations and that were first used by Michelson to calculate the standard meter.

The narrowest line of the cadmium spectrum; the red line has the purest radiation.

The production of visible light by infrared radiation whereby the light is produced by heat and not by any direct change in wavelength; the transformation is indirect.

Name originally given to the sun's infrared radiation by Sir William Herschel in his Philosophical Transactions of 1800.

Light produced when a metal is bombarded with high-velocity electrons causing small amounts of the metal to vaporize and emit radiation. Also known as electronoluminescence.

In an interferogram, an intense portion of the recording that corresponds in size to the amount of infrared radiation incident on the detector.

An instrument that detects high-energy charged particles by analysis of the Cerenkov radiation that they emit.

A photoelectric detector consisting of a glass tube internally coated with a low conductance material. Voltage applied along the tube causes photoemission from the photocathode at the end of the tube...

A light-sensitive detector having a chemical compound that reacts when exposed to light. It is used in photochemistry and relies on the chemical reaction to determine the amount of incident radiation.

Scanning characterized by the generation of a plane or right circular cone with a vertex angle of about 180° by the direction of maximum radiation.

The desensitization of the first photographic exposure after it has been subjected to high-intensity radiation.

Glass that transmits near-ultraviolet radiation but is opaque in the visible region. Also known as woods glass.

A reticle carrying patterns of various forms that can be rotated in an optical beam to cause variations in the intensity of the beam. It also is used in infrared detectors to scan the object field...

A light source that is capable of producing radiation with waves vibrating in phase. The laser is an example of a coherent light source.

A cathode that emits electrons, not with the influence of heat radiation, but by means of a high-voltage gradient at its surface.

A mirror whose coating serves to reflect visible radiation while transmitting the infrared.

1. The process of aligning the optical axes of optical systems to the reference mechanical axes or surfaces of an instrument. 2. The adjustment of two or more optical axes with respect to each other....

A filter that serves to alter the color temperature and the mired value of the radiation emitted by a source.

A type of compound microscope that uses three visible wavelengths to translate details produced by invisible radiation.

The phenomenon observed by A.H. Compton in 1923 -- that some scattered radiation possesses a longer wavelength and correspondingly smaller frequency than the incident radiation. It may be described...

The radiation spectrum of matter found in condensed states, liquid or solid, that is continuous and not a line spectrum. The details of this spectrum are almost independent of the matter emitting the...

A laser that emits radiation continuously rather than in short bursts, as in a pulsed laser.

Translucent collector developed to compensate for the partial blocking of a flat surface's collection angle that normally occurs in spectroradiometry. The device samples radiant flux according to the...

A technique used in integrated optics where a groove is cut on a substrate surface and covered by a thin film to facilitate the construction of filters, resonators, beamsplitters and grating couplers...

Plastic in which the polymer chains become irreversibly joined during molding. The cross-linking can be achieved by heating, chemical agents or irradiation.

The use of chemicals or radiation to induce a desired change in a substance; e.g., some optical adhesives are set by exposure to ultraviolet light and are said to be UV-curing.