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Intentionally alternating the intensity of a display element in a graphic display device.
An extended bubble or seed on glass, elliptically shaped and more than one-quarter inch (6.3 mm) in length.
A group of adjacent pixels in an image representing the same value, as all black in a binary image.
A supporting member used to hold optical parts during grinding and polishing. It also describes the assemblage of optical parts on the supporting member; e.g., a block of lenses or block of prisms.
block reek
A type of scratch.
The process whereby blanks are attached to a block in a position for grinding or polishing.
blocking cement
An adhesive used to hold optical elements to blocking tools. It is usually a thermoplastic substance such as resin, beeswax, pitch or shellac.
blocking material
Pitch, wax, resin or other cement suitable for holding optical parts to a spindle during grinding and polishing processes.
blocking pitch
An adhesive used to affix optical elements to an approximately shaped body -- usually of cast iron.
blocking shaper
A convex, concave or flat cast iron form that is used to shape a soft mold block of optical components.
blocking tool
An instrument used to support optical parts to be cemented, or to be mounted in plaster.
The loss of focus of a camera sensor because of excessive brightness, characterized by the enlargement of spot size and halation on a cathode-ray tube.
blown fiber
A technique developed by British Telecom in which the viscous drag of air is used to install optical fibers in narrow plastic tubes.
blue diode laser
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,...
blue noise
Noise over a specified frequency range, in which the spectral density is proportional to the frequency instead of being independent of it, as in white noise.
An edging stone having a relatively coarse abrasive.
blur circle
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...
In the optical field, a piece of glass to which a lens or prism is cemented. The unit is ground and polished as a whole to obtain a sharp edge on the finished piece.
Bohr's frequency relation
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 bolometer that serves to record. The photographic record formed by the bolometer may be called bolograph or bologram.
A thermometric instrument used for the detection and measurement of radiant energy. Its essential component is a short narrow strip covered with a dead black absorbing coating and mounted at the...
Boltzmann's constant
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.
An instrument that determines, or allows a bombardier to determine, the point in the plane's line of flight at which a bomb must be released to hit a specified target.
The central hole running the full length of a laser capillary tube, in which electrical discharge and laser action take place. Also a similar hole in a hollow waveguide or a microchannel plate.
A device for the internal inspection of hard-to-get-at mechanical parts, such as rifle barrels, sewer pipes, oil wells, or gas mains. The long narrow tube used contains a telescope system with as...
The alignment process that makes the optical axes of two related systems parallel to each other. Also, making the optical axis parallel to a related weapon system axis.
borosilicate glass
A strong, heat-resistant glass that contains a minimum of 5 percent boric oxide.
Bose-Einstein condensate
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 boson is a type of fundamental particle that follows Bose-Einstein statistics, which dictate the statistical distribution of identical particles with integer spin. Bosons are one of the two main...
Bouguer's law -> Lambert's absorption law
Transmittance of a solution, or internal transmittance of a transparent solid, is an exponential function of the thickness of the layer.
1. A group of optical fibers that are fused and then treated to produce a vacuum-tight optical fiber cone or plate. 2. An artificial crystal in its raw state, after generation but prior to cutting or...
bound mode -> guided mode
In an optical waveguide, a mode whose field decays monotonically in the transverse direction everywhere external to the core and which does not lose power to radiation. Also called bound mode.
boundary extraction
In optical character recognition, an intermediate step between character location and feature extraction.
bowl-feed machine
A polishing machine in which the rouge slurry is contained in a bowl and is constantly diverted mechanically so that it flows over the work.
box camera
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...
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...
Boys camera
A camera system for recording lightning.
Brace prism
A compound prism composed of two 30° prisms, one of which is partially coated with a suitable opaque metal of high reflecting power. The prisms are cemented with Canada balsam so that the coated...
Brace-Lemon spectrophotometer
A spectrophotometer having a pair of identical collimators with two Glan polarizing prisms, one fixed in azimuth and the other rotatable, set in one collimator. A Brace prism serves as the dispersive...
In photography, the technique of taking multiple pictures of the same subject at different exposures to compensate for exposure miscalculations. Automatic bracketing is a feature on some cameras.
Bragg angle -> Bragg scattering
The scattering of x-rays by the regularly spaced atoms in a crystal. The angle at which the reflection occurs is known as the Bragg angle.
Bragg cell -> acousto-optic modulator
An acousto-optic modulator (AOM) is a device that utilizes the acousto-optic effect to modulate the amplitude, phase, frequency, or polarization of a laser beam or other coherent light source. It...
Bragg grating
A filter that separates light into many colors via Bragg's law. Generally refers to a fiber Bragg grating used in optical communications to separate wavelengths.
Bragg method of crystal analysis
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...
Bragg scattering
The scattering of x-rays by the regularly spaced atoms in a crystal. The angle at which the reflection occurs is known as the Bragg angle.
Bragg spectrometer -> ionization spectrometer
Also known as the Bragg spectrometer. A system used for the x-ray analysis of crystal structure. In the instrument, a homogeneous beam of x-rays is directed on the known face of a crystal and the...
Bragg's law
The law expressing the condition under which a crystal will reflect a beam of x-rays with the greatest amount of distinction or resolution and, at the same time, denoting the angle at which 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.
Bravais-Miller index
One of the constants h, k, f or I, used to demonstrate any set of parallel planes in a crystal of the hexagonal system.
An experimental model of an electrical circuit or complex assembly; a prototype.

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