Photonics Dictionary: B

The term used in reference to vacuum systems using oil and diffusion pumps, describes the migration of pump fluids and their decomposition products into the vacuum chamber.

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

A camera that uses multiple exposures to record the trajectory of an ordnance from a ground-level position.

Any instrument or system carried by a balloon to the upper atmosphere to measure and record atmospheric information, such as radiation observations, while reducing atmospheric interference.

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

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

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

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...

The glossy appearance of an object viewed, because of the binocular combination of two very unlike colors.

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...

A matrix-controlled display that has information storage at the display surface, and requires that an element be addressed only once to assure that it is on or off.

Characteristic of a reflector that reflects light along a different line or lines than that of the incident ray.

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...

An extended bubble or seed on glass, elliptically shaped and more than one-quarter inch (6.3 mm) in length.

An edging stone having a relatively coarse abrasive.

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 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...

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...

Electromagnetic radiation that is emitted by an electron as it is accelerated or decelerated while moving through the electric field of an ion.

A parallel plate of glass in such a position that the refracted and reflected rays of incident parallel light are mutually perpendicular. In this situation the reflected light is plane polarized, and...

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 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.

A sound wave that travels through a piezoelectric material.

A high-frequency pulse-rate laser with an output limited by the heat capacity of the laser medium. Instead of having continuous cooling, the laser operates until the medium reaches a maximum...

The measure used in vacuum technology to quantify the total pressure capacity of the ferrofluidic seal before it fails.

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

Calculates the exponential growth of the least stable spatial frequency in a laser beam, and is the numerical equivalent of the nonlinear phase shift along the laser system's optical axis.

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...

The rule stating that positive uniaxial crystals have greater absorption with respect to the extraordinary component of light, whereas negative crystals have greater absorption for the ordinary...

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...

The principle stating that two diffraction screens, one being exactly the negative of the other, will form the same diffraction patterns.

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

A glass substrate that has its rear surface coated with a reflective coating. Also known as a back-surface mirror.

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...

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

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...

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...

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

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

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