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Binoculars are optical instruments used for magnifying distant objects by using two parallel telescopes mounted side by side. They allow users to see distant objects more clearly and in greater...
A term pertaining to devices (generally optical) designed for use with both eyes viewing through a single exit pupil. The term may be distinguished from binocular in that biocular instruments contain...
Bioelectricity refers to the electrical potentials and currents generated by biological processes within living organisms. These electrical phenomena arise from the movement of ions across cell...
Bioluminescence is a natural phenomenon in which living organisms produce and emit light through a chemical reaction occurring within their bodies. This light emission is typically the result of a...
A biomarker, short for biological marker, refers to a measurable and quantifiable indicator of a biological condition, process, or response. Biomarkers can be substances or characteristics that are...
Biometrics refers to the automated recognition of individuals based on their physiological or behavioral characteristics. These unique attributes are used to verify or identify individuals, often in...
Biomimicry, or biomimetic design, is the practice of emulating natural processes, systems, and structures found in biological organisms to solve human problems or create innovative technologies. It...
The application of observed operational processes of sophisticated living organisms to mechanical and electrical systems in order to analogize capabilities or efficiency.
The technology that deals with the interaction of organic materials with light and other forms of radiant energy whose quantum unit is the photon. This includes the emission, detection, absorption,...
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...
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.
biplanar lens
Electron lens consisting of an homogeneous axial electric field.
Refers to transistors in which the working current flows through two types of semiconductor material: N- and P-type. In bipolar transistors, the working current consists of both positive and negative...
A piece of glass polished flat on one side, with a pair of polished faces that form an angle close to 180° on the other side, the dividing edge running down the middle of the plate. It is used...
biprism interference
Light interference fringes that can be viewed on a screen near a biprism.
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.
bismuth silicon oxide
A photorefractive material used in image processing, holography and optical switching.
bispheric condenser -> dark-field condenser
A condenser that forms a hollow cone-shaped beam of light with its focal point in the plane of the specimen. If it is used with an objective having a numerical aperture lower than the minimum...
bistability -> optical bistability
The phenomenon that can render an optical resonator the equivalent of a semiconductor flip-flop. A bistable device will remain stable in two optical states, one of high transmission and another of...
bistable display
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.
bistatic reflectivity
Characteristic of a reflector that reflects light along a different line or lines than that of the incident ray.
A contraction of binary digit; the fundamental unit of digital computing, a bit is either 1 or 0, expressing the binary state of on or off, true or false, etc.
bit boundary block transfer
A data transfer function that moves a rectangular group of pixels between bit maps. Often used in displaying cursors and pop-up windows.
bit error rate
The ratio of the number of bits received incorrectly to the total number of bits transmitted digitally in a system.
bit mapping
In computer graphics, the assignment of each pixel on a display screen to its own switch in the computer memory.
bitoric lens
A lens, both surfaces of which are ground and polished into a toric or cylindrical form.
Bjerrum screen
In ophthalmic practice, an instrument that determines the boundaries of the field of view. It is composed of a 2-m square of black velvet with a white spot center at which the patient, 1 m away,...
black hole
A cosmic phenomenon in which the mass and density of a star pass a critical point so that the escape velocity matches the speed of light. For this reason, light and matter are "captured'' by the...
black level
The level of the television picture signal that corresponds to the maximum limit of black peaks.
black light
Radiation from the invisible (usually ultraviolet) region of the spectrum.
black surface enclosure
An enclosure whose walls are coated to absorb completely all radiation striking them.
An ideal body that completely absorbs all radiant energy striking it and, therefore, appears perfectly black at all wavelengths. The radiation emitted by such a body when heated is referred to as...
blackbody locus
With respect to a chromaticity diagram, this is the locus of points that represent the chromaticities of blackbodies possessing different color temperatures.
blackbody simulator
A source that attempts to create the characteristics of an ideal blackbody. It consists of a cavity, generally spherical, made of an opaque material and insulated from thermal effects, with a small...
blackbody source
A blackbody source, often simply referred to as a blackbody, is a theoretical or practical physical object that absorbs all electromagnetic radiation incident upon it and emits radiation in a...
blacking -> optical blacking
A light absorbing material applied to ground optical surfaces during the process of making that surface non reflective. Such material should have a refractive index as high as that of the underlying...
A piece of glass, quartz or other transparent material formed roughly by molding or cutting into the approximate shape and size of the finished part.
The process by which the raster beam in a video tube is cut off during the retracing and sync periods.
1. A plane that forms one side of the groove ruled on a diffraction grating. 2. To form the individual grooves of a grating with flat smooth faces, inclined to the surface by an angle known as the...
blaze height
Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of a series of closely spaced parallel grooves or slits. The blaze height is...
blaze wavelength
The light wavelength for which the direction of reflectance from the groove face is identical to the angle of diffraction for a specified angle of incidence.
bleach (or bleacher)
A chemical used in the developing of positive photographs that incites oxidation and thereby dissolves the negative silver to vary tone, color and intensity.
bleaching -> saturable absorber
A saturable absorber is a type of optical device that exhibits variable absorption properties depending on the intensity of incident light. In essence, it becomes less absorbent as the light...
blind approach beacon system
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...
blind spot
The spot on the retina where the optic nerve is attached; it is incapable of sensing light because of the absence of light receptors.
The inability to perceive visual images (visible radiant energy). In human beings, blindness is defined as a visual acuity of less than one-tenth normal vision.
blink comparator
An optical system that rapidly alternates two similar pictures or scenes to permit the detection of small dissimilarities between them.
Intentionally alternating the intensity of a display element in a graphic display device.

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