Photonics Dictionary: B

The ability of the two eyes to see an object from two slightly different points of view. This difference allows an individual to perceive the depth and dimension of the object in view.

A cathode-ray display where information is represented visually as spots. Each spot's location is represented by a horizontal coordinate showing its bearing angle, and a vertical coordinate showing...

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...

A channel for communication with the source in an otherwise unidirectional network, such as a channel that provides interactive features in a cable television network.

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...

The intensity of the light in the scene behind an object being viewed.

In a mechanical system, any lost motion between driving and driven elements due to clearance between parts.

The forming of a clear silhouette of an object by placing a light source behind it. Used in machine vision when surface features of an object are not important.

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...

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...

An opaque shielding device designed to reduce the effect of stray light on an optical system.

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

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...

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

An optical scanning device designed to read information printed in the form of bars of different size by detection and processing of the varying reflectivity of light in the barcode.

A crystalline material used in piezoelectric devices.

In aerial photography, the ratio derived from a stereoscopic pair of photographs that represents the air-base length divided by the flight altitude.

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...

The scale for floating hydrometers used to measure the specific gravity of a polishing suspension. The depth of immersion is a linear function of the inverse of the density. The Baume scale is linear...

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.

A device designed to decrease flux density or power per unit area of a light beam through absorption and scattering of the beam.

A device used to alter the shape of or energy distribution within a beam of radiation.

A device (e.g., prisms, lenses, tubes) used to align a beam in a system.

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...

Laser light show effects equipment including optics and mechanical devices that reflect, position or distort the laser beam, but not including the laser itself.

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....

The signal formed when two signals, such as light waves, of different frequencies are present simultaneously in a nonlinear device. The frequency of the beat is equal to the difference in frequency...

Device used to measure the numerical aperture of a microscope, composed of a 14-mm-thick glass block with numerical aperture gradations carved onto its lower surface.

Activity of a radionuclide having one spontaneous nuclear transition per second.

A device used to compare the luminous intensities of two sources by locating a point between the two light sources where the produced flux densities are equal. The luminous intensities of the two...

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...

A dielectric ceramic material used in laser capillary tubes because of its high electrical resistivity and high thermal conductivity (half that of copper).

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...

The use of a short-duration electron beam to record high-speed events that occur in microscopic objects made of materials that emit visible fluorescence during electron bombardment. The method is...

1. To influence to a single direction. 2. Voltage that is applied to a solid-state device.

A birefringent crystal having two axes along which there is an absence of double refraction. Mica, sulphur and turquoise are biaxial crystals.

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

A lens having each of its outer faces curved inward.

A lens having each of its outer faces curved outward.

Unified notation for specification of reflectance in terms of both incident- and reflected-beam geometry; i.e., the ratio of reflected radiance in direction toward the viewer to the irradiance in...