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Photonics Dictionary: B

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beam shuttle
A set of mirrors mounted on solenoids to move them into and out of the path of a laser beam, making it possible for multiple workstations to alternate using the single laser source.
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...
beam table
Laser light show effects equipment including optics and mechanical devices that reflect, position or distort the laser beam, but not including the laser itself.
beam waist
That point in a Gaussian beam where the wavefront has a curvature of zero and the beam diameter is a minimum.
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
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...
BEAT
bistable etalon by absorbing transmission
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...
beauty defect
A defect on or in an optical element that does not appreciably impair the function of the surface.
BEC
Bose-Einstein condensates
Becke apertometer
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.
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
Activity of a radionuclide having one spontaneous nuclear transition per second.
Becquerel effect
The intensification of a latent image, because of exposure to light to which the emulsion is otherwise insensitive.
Beer's law
Transmittance of a stable solution is an exponential function of the concentration of the absorbing solute.
Beer-Lambert law
Combination of Beer's and Lambert's (absorption) laws.
BEL
yttrium lanthanum beryllate
bellows
In optics, a collapsible structure situated between the lens and film of a camera to allow variation of the distance between them while preventing surrounding light from exposing the film.
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,...
bench photometer
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...
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 --...
bend loss
The loss of optical power in an optical fiber because radiation escapes through its bends. The radiation loss caused by fiber bending is proportional to the bend radius.
bend radius
The radius of curvature that an optical fiber can bend without breaking.
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...
BER
bit error rate
Bernoulli terms
Mathematical definition for the changes that occur between potential and kinetic energy. These formulas express wave motion.
BERT
basic energy reduction technology; bit-error-rate test
Bertrand lens
A small convergent lens, located between the objective and eyepiece of a microscope, that focuses an image of the upper focal plane of the objective in the focal plane of the eyepiece. It is commonly...
beryllium oxide
A dielectric ceramic material used in laser capillary tubes because of its high electrical resistivity and high thermal conductivity (half that of copper).
Bessel functions
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...
BEST
business EDR system technique
beta fluorography
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...
beta radiation
The high-speed electrons and positrons emitted by radioactive materials.
beta site
A facility selected by mutual agreement of the user and the prospective vendor to test a prototype before it is offered for sale.
beta-ray spectrometer
An instrument for the detection of the energy distribution of b-particles and secondary electrons.
betatron
An instrument designed to produce very hard x-rays by the acceleration of electrons in a varying magnetic field.
bevel
A chamfer ground on the edge of a lens or prism. Bevels are used to prevent chipping or to achieve a mechanical fit.
bevel face width
The actual width of a bevel rather than its width projected along the lens aperture.
BFD
back focal distance
BFL
back focal length
BFS
best fit sphere
BFSK
binary frequency shift keying
BGO
bismuth germanium oxide
bi-quartz
A double block formed by placing two adjoining, equally thick sections of quartz, one being dextrorotary, the other levorotary, over the analyzer of a polariscope. In this way, polarization tints may...
bias
1. To influence to a single direction. 2. Voltage that is applied to a solid-state device.
bias buildup
Degradation factor in coherent light systems where the amplitude of the recorded signal is decreased as the number of object points is increased, resulting in poor noise performance.
bias frame
A frame taken with a CCD camera over an exposure length of zero seconds with the lens cap on or the shutter closed and no light reaching the sensor. This frame shows the electronic noise in the...

Photonics DictionaryB

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