Photonics Dictionary

A CCD that has been reduced in thickness by etching so that light passes through the back layers of the CCD. This type of CCD typically has higher sensitivity, especially to blue light, and higher...

Backscatter refers to the phenomenon in which radiation or waves are scattered backward, opposite to the direction of the incident beam. This occurs when the incident radiation encounters a target or...

Fraction of light counter propagating collinear with the incident source. Processes considering backscattering are Raman, Brillouin, Rayleigh and Mie.

A light-harvesting protein found in the purple membrane of a micro-organism called Halobacterium halobium. The protein undergoes a photocycle that involves several binary photochemical reactions that...

The elimination of gases from the surfaces of a vacuum system by heating the surfaces when the pumping phase is occurring.

In semiconductor physics, the term bandgap refers to the energy range in a material where no electronic states are allowed. It represents the energy difference between the valence band, which is the...

A negative lens used to increase the effective focal length of a telescope objective.

The negative distortion that causes a square grid pattern to be imaged as barrel-shaped.

In the fabrication of an optical fiber, a layer that can be used to create a boundary against OH-ion diffusion into the core.

A coupling mechanism designed to quickly lock a connector into an adaptor or a lens into a lens mount. Typically coupling is accomplished by less than a quarter turn of the component being mounted.

Bardeen-Cooper-Schrieffer theory of superconductivity, based on the notion that electrons with opposite momentum and spin are paired as a result of forces arising from lattice vibrations. The theory...

A device, either visual or electronic, that emits signals to identify set positions for use in the navigation of aircraft and ships along flight paths and channels, or as a warning against entering a...

A system of beacons used in navigation.

1. A geometrical arrangement of two or more light beams for use in laser shows, object detection or other applications requiring arrayed multiple beams. 2. A mathematical 2 X 2 or 3 X 3 matrix for...

A device that measures the spatial distribution of energy perpendicular to the propagation path of a radiant beam. An energy or power meter is typically used to monitor the amount of light passing...

Beam profiling is a technique used to characterize and analyze the spatial intensity distribution of a laser beam. It involves measuring and visualizing how the optical power or intensity is...

A beam shaper is an optical device or system designed to modify the spatial profile or intensity distribution of a laser or light beam. The goal is to transform the incoming beam into a desired shape...

That point in a Gaussian beam where the wavefront has a curvature of zero and the beam diameter is a minimum.

A band of light that appears along the outer edge of a transparent material under microscopic investigation and that moves toward higher refractive indices as the microscope's focus is raised, and...

Mathematical compensation for the nonhydrogenic behavior of recombination radiation levels of gases, based on the quantum effect method.

An imaging technique that labels all gray pixels as either black or white before processing begins.

Heatless light emissions from living organisms caused by the combination of oxygen and pigments such as luciferin.

Biometrics refers to the automated recognition of individuals based on their physiological or behavioral characteristics. These unique attributes are used to verify or identify individuals, often in...

The application of observed operational processes of sophisticated living organisms to mechanical and electrical systems in order to analogize capabilities or efficiency.

The technology that deals with the interaction of organic materials with light and other forms of radiant energy whose quantum unit is the photon. This includes the emission, detection, absorption,...

Refers to transistors in which the working current flows through two types of semiconductor material: N- and P-type. In bipolar transistors, the working current consists of both positive and negative...

Birefringence is an optical property of certain materials that causes them to exhibit different refractive indices for light of different polarizations. In other words, when light passes through a...

A blackbody source, often simply referred to as a blackbody, is a theoretical or practical physical object that absorbs all electromagnetic radiation incident upon it and emits radiation in a...

A chemical used in the developing of positive photographs that incites oxidation and thereby dissolves the negative silver to vary tone, color and intensity.

A ground-based navigation beacon that emits pulsed signals which are picked up by aircraft making an instrument (blind) approach in landing. The signal is transmitted to the aircraft's L-scan...

A blue diode laser is a type of semiconductor laser that emits light in the blue wavelength range of the electromagnetic spectrum, typically between 400 and 500 nanometers. Diode lasers are compact,...

A constant equal to the universal gas constant divided by the Avogadro number. It is approximately equal to 1.38 x 10-23 J/K and is commonly expressed by the symbol k.

A device for the internal inspection of hard-to-get-at mechanical parts, such as rifle barrels, sewer pipes, oil wells, or gas mains. The long narrow tube used contains a telescope system with as...

A Bose-Einstein condensate (BEC) is a state of matter that forms at temperatures close to absolute zero. It is named after Satyendra Nath Bose and Albert Einstein, who independently predicted the...

An instrument for detecting and analyzing repetitive signals. Using a fixed time delay or "gate," the input signal is sampled numerous times and averaged to increase the ratio of the...

A filter that separates light into many colors via Bragg's law. Generally refers to a fiber Bragg grating used in optical communications to separate wavelengths.

A technique in which a beam of x-rays is directed against a crystal, the atoms of which, because of their lattice arrangement, reflect the ray in the same way as a series of plane surfaces. If the...

A sheet of thin brass, one edge of which has been accurately cut to a known and marked circular radius. It is used to check the radius of curvature of a rough-ground lens by contact.

In avalanche photodiodes, the point at which an increase in the reverse bias voltage causes the current gain to approach infinity.

A breakout cable, also known as a fan-out cable or breakout assembly, is a type of cable that combines multiple individual cables into a single, larger cable. The breakout cable is designed to...

For light incident on a plane boundary between two regions having different refractive indices, the angle of incidence at which the reflectance is zero for light that has its electrical field vector...

The illumination generally used in microscopy, whereby the specimen appears dark against a light background.

An emission spectrum consisting of bright bands against a dark background.

Brightfield refers to a type of microscopy and imaging technique in which the specimen is illuminated with a white light source, and the image is observed or captured against a bright background. In...