Type

Browse by Letter

Bristol Instruments, Inc. - 872 Series High-Res 4/24 MR

130 terms

Photonics Dictionary: B

Clear All Filters x GE x B x
beaconage

A system of beacons used in navigation.

beam divergence

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.

binary image

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

biplanar image tube

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

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...

birefringent crystal -> doubly refracting crystal

A transparent crystalline substance that is anisotropic relative to the velocity of light.

birefringent filter

A filter that transmits light in a series of sharp, widely spaced wavelength bands by its sandwich construction of alternating layers of polarizing films and plates cut from birefringent crystal.

boxcar averager

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...

brass gauge

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.

breakdown voltage

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

Brewster's fringes

The fringes used in the Jamin interferometer and produced by light that has been internally and externally reflected by two plane-parallel plates, inclined toward each other at a small angle.

bright-field image

An optical image having a brightly lit background.

broken edge

A chamfer or protective bevel.

beam spread -> divergence

1. In optics, the bending of rays away from each other. 2. In lasers, the spreading of a laser beam with increased distance from the exit aperture. Also called beam spread. 3. In a binocular...

Babinet compensator

A device containing two opposed quartz wedges of equal angle, one wedge being movable along its length by a micrometer screw. The wedges are cut so that their fast directions are along, and...

back focal length

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

backlight compensation

The ability of a camera to compensate in cases where a subject with a large amount of background light would otherwise be obscured by blooming or silhouetting.

backreflection -> narcissus

A defect in infrared systems that appears as a dark circular area on a displayed image, caused by radiation reflecting into a detector. It can be reduced by low-reflective coatings or by altering the...

backscatter

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...

backward-wave oscillator

An amplifying device with a wide tuning range in which an electron gun sends a beam of electrons into a slow-wave structure. The electron beam and the electromagnetic wave move in opposite directions...

Baker corrector

A two-mirror corrector for a parabolic primary mirror that provides anastigmatic performance for large astronomical telescopes.

ball lens

A ball lens is a small, spherical optical component typically made of glass or other transparent materials. It is characterized by its spherical shape, with both its front and back surfaces forming...

ballast resistance

In a laser, the series resistance necessary for a stable electrical discharge.

BAMGAR

barium magnesium germanate garnet

band head

The measured wavelength of the most distinct edge of a spectral band.

band-elimination filter

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

bandgap

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...

bandpass

The range of frequencies that will pass through a filter or other device. Synonymous with passband.

bandstop filter -> band-elimination filter

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

bandwidth

The range of frequencies over which a particular instrument is designed to function within specified limits. See also fiber bandwidth.

Barlow lens

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

barrel distortion

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

bathymetric lidar

Bathymetric lidar is a remote sensing technique used to measure the depth of water bodies and map underwater terrain features. It employs lidar (Light Detection and Ranging) technology, which uses...

beam diameter

1. Calculated distance between two exactly opposed points on a beam at a chosen fraction of peak power (typically 1/e2). 2. The diameter of a circular aperture that will pass a specified percentage...

beam divider -> beamsplitter

A beamsplitter is an optical device used to divide a beam of light into two or more separate beams, typically by reflecting a portion of the incident light while transmitting the remainder....

beam matrix

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...

beam optics -> Gaussian beam optics

The area of optics that deals with the propagation of Gaussian laser beams in free space, or any general medium - i.e. lenses- under the paraxial (small divergence angle) approximations. Gaussian...

beam profiling

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...

beam shaper

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...

beam-addressable technology

The application of reversible writing with a laser beam on particular storage materials. In one method, an amorphous film is heated and then crystallized for writing. Bubble writing involves the...

beamsplitter

A beamsplitter is an optical device used to divide a beam of light into two or more separate beams, typically by reflecting a portion of the incident light while transmitting the remainder....

beamsplitting block

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

beamwidth

The angular width of a radiation beam. With respect to a conical beam of light, it is the vertex angle of the cone. The beamwidth is a measure of the rate of divergence or convergence of a light...

beat length

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...

Becke line

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...

Becquerel effect

The intensification of a latent image, because of exposure to light to which the emulsion is otherwise insensitive.

bench -> 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,...

bend -> deformation constant

Any of the constants that relate the tendency of the director to remain parallel to restoring torques throughout the media. The three constants of importance in liquid crystal displays are: splay --...

bending of light

1. That action occurring when light passes through an optical interface at other than normal incidence, i.e., refraction. 2. The curving of a path of light that passes close by a massive object, due...

Bernoulli terms

Mathematical definition for the changes that occur between potential and kinetic energy. These formulas express wave motion.

Photonics DictionaryB