Photonics Dictionary: C

The electron beam tube of a television camera that converts an optical image into a pattern of electrostatic charges and then scans the pattern to produce a corresponding electronic signal for...

A light-tight box that receives light from an object or scene and focuses it to form an image on a light-sensitive material or a detector. The camera generally contains a lens of variable aperture...

A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola. The image formed is free of spherical aberration and color and is located...

A vacuum tube with an electron gun at one end and a fluorescent screen at the other. Electrons emitted from a heated filament are accelerated by a series of annular anodes at progressively higher...

A surface that envelops a bundle of rays or bundle of normals to the wave surface. It may be observed as a hollow, luminous cusp in a turbid medium.

A charge-coupled device (CCD) is a type of electronic image sensor used in various imaging devices, including digital cameras, camcorders, and scientific instruments. It consists of an integrated...

Chemical vapor deposition is a process of applying dopants to a glass bait by flame reactions of gaseous compounds. See also outside vapor-phase oxidation; inside vapor-phase oxidation.

The ray that passes through the center of the aperture stop in an optical system. It often is called the principal ray of an oblique beam.

The state of a liquid crystal in which the molecules are arranged in layers with their long axes in the plane of each layer. The alignment in each layer is parallel and the alignment in adjacent...

In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.

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

That part of an infrared detector-Dewar assembly that limits the solid angle viewed by the sensor; it is maintained at a uniformly cold temperature so that no thermal energy is emitted. Also known as...

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....

An optical instrument consisting of a well- corrected objective lens or mirror with a light source and or object/image (i.e. illuminated slit or retical) at its focal plane. Collimators are used to...

A colorimeter is a device used to measure and quantify the color characteristics of an object or a light source. It provides objective and standardized color information, typically expressed in terms...

A lens aberration, resulting from different magnifications in the various lens zones, that occurs in that part of the image field that is some distance from the principal axis of the system....

A confocal resonator, also known as a confocal cavity or confocal laser resonator, is a type of optical resonator configuration used in laser systems. The term confocal in this context refers to the...

Hardware installed on fiber cable ends to provide cable attachment to a transmitter, receiver or other cable. Usually a device that can be connected and disconnected repeatedly.

The apparent difference in brightness between light and dark areas of an image. For a light target against a dark background, contrast is computed as follows: where Lt is the luminance of the...

The simplest lens in which all primary aberrations may be corrected. It consists of two positive crown elements on either side of, and spaced away from, a negative flint element.

A corner cube, also known as a corner reflector or retroreflector prism, is a type of optical device used to reflect light or electromagnetic waves back towards their source with minimal deviation in...

A compound prism formed by cementing together two 30° prisms, one of right-handed and one of left-handed quartz. It has good ultraviolet-transmitting qualities and no double refraction.

The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is...

Illumination in which the light source is imaged at the object.

A lens aberration that causes a flat object surface to be imaged onto a curved surface rather than a plane.

A lens aberration in which the focal length varies radially outward from the center of the field. It has the effect of making a straight tangential line in the object appear curved in the image,...