Photonics Dictionary: B

A biomarker, short for biological marker, refers to a measurable and quantifiable indicator of a biological condition, process, or response. Biomarkers can be substances or characteristics that are...

The distance from the final optic within a system to the rear image point of the system. See focal length.

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...

A spectrum that originates from molecules and that is composed of bands which, in turn, consist of many closely spaced lines. Band spectra are used to determine nuclear spin and statistics, and...

A filter that suppresses a given range of frequencies, transmitting only those above and below that band. Also called bandstop filter.

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.

The simplest method of transmission on a local area network. The entire bandwidth of the cable is used to transmit a single unmodulated digital signal. Baseband transmission is capable of...

1. A bundle of light rays that may be parallel, converging or diverging. 2. A concentrated, unidirectional stream of particles. 3. A concentrated, unidirectional flow of electromagnetic waves.

Increase in the diameter of an initially collimated beam, as measured in milliradians (mrad) at specified points; i.e., where irradiance is a given fraction (often 1/e2) of peak irradiance.

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...

A beamsplitter is an optical device for dividing a beam into two or more separate beams. A simple beamsplitter may be a very thin sheet of glass inserted in the beam at an angle to divert a portion...

A glass block that produces stationary fringes in the region crossed by incident light beams.

A characteristic of optical fiber used to calculate the fiber's ability to maintain polarization. The beat length describes the length required for the polarization to rotate 360 degrees. For a given...

Two formulas used in diffractometer analysis, the first giving the individual diffraction patterns of each aperture, the second representing the constant of the degree of an incoherent circular...

An experimental lens used to produce interference fringes. A positive lens is cut into halves along its center, and the halves are separated. This produces a double image of a slit source set...

A type of piezoelectric translator that uses two thin strips of piezoelectric material, one expanding while the other contracts, to produce movement.

A digitized image consisting of just two brightness levels, as black and white, represented in memory as zeros and ones.

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

A microscope designed with two eyepieces (oculars), permitting the use of both eyes when viewing through the instrument.

A term pertaining to devices (generally optical) designed for use with both eyes viewing through a single exit pupil. The term may be distinguished from binocular in that biocular instruments contain...

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 action of a biological system responding to a single or multiple coherent particles of light produced from a laser source. Examples of laser biostimulation include: retinal interaction of light...

Also called proximity focus image intensifier. A compact image intensifier that utilizes a microchannel plate intensification stage. This is an in-line device that does not invert the image.

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 contraction of binary digit; the fundamental unit of digital computing, a bit is either 1 or 0, expressing the binary state of on or off, true or false, etc.

The ratio of the number of bits received incorrectly to the total number of bits transmitted digitally in a system.

In computer graphics, the assignment of each pixel on a display screen to its own switch in the computer memory.

Radiation from the invisible (usually ultraviolet) region of the spectrum.

A source that attempts to create the characteristics of an ideal blackbody. It consists of a cavity, generally spherical, made of an opaque material and insulated from thermal effects, with a small...

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...

1. A plane that forms one side of the groove ruled on a diffraction grating. 2. To form the individual grooves of a grating with flat smooth faces, inclined to the surface by an angle known as the...

Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of a series of closely spaced parallel grooves or slits. The blaze height is...

Intentionally alternating the intensity of a display element in a graphic display device.

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,...

An edging stone having a relatively coarse abrasive.

A blur circle refers to the out-of-focus region in an image captured by an optical system. When an object in a scene is not in perfect focus, its image is spread out into a circular shape on the...

The law given by the formula: that is, the frequency of radiation emitted or absorbed by a system when E2 and E1 are the energies of the states among which transition takes place, and h is...

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...

The simplest, most inexpensive type of camera, which is shaped as an oblong or square box, containing the simplest lens, shutter and viewfinder, as well as the most elementary means of registering...