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BT Dictionary Terms

pyroelectric pulse detector
A current-source thermal detector used to detect and study the pulses obtained from particular lasers.
minimum visible
The smallest area of uniform brightness that can be seen by the eye. It is measured in terms of the solid angle subtended by...
texel
A contraction for "texture element." A base unit used in computer graphics that defines the surface of three-dimensional...
relative brightness
A figure of merit corresponding to the amount of light seen by a viewer through binoculars. A higher number indicates a...
aerial survey
The creation of a planned sequence of data input that is obtained while airborne for use in aerial photogrammetry and other...
smectic phase
A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the...
Raman fiber probe
A flexible fiber cable with a small diameter that transports light from the excitation laser to the target. Used in Raman...
stereoscope
A small instrument containing a picture support and a pair of magnifying lenses so arranged that the left eye sees only the...
array processor
In image processing, a specially designed programmable computer peripheral that attaches to the host system for the purpose...
dark frame
A frame taken to identify electronic noise in a CCD imaging device. A dark frame is recorded without exposing the CCD to any...
volumetric imaging
Volumetric imaging refers to the capture, visualization, and analysis of three-dimensional (3D) information from a volume of...
morphological processing
A set of algorithms used to study the structural and spatial characteristics of objects in a digitized image for...
design and engineering consulting services
Design and engineering consulting services refer to professional services provided by specialized firms or individuals to...
atmospheric refraction correlation
Formulaic compensation to correct laser ranging data for the effects of horizontal refractivity gradients; it requires the...
microwave mapping
The pattern of microwave field intensity that can be obtained by detecting the minute expansion of a microwave absorber slab...
accelerometer
An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms,...
flash sensitometer
A sensitometer that utilizes an electronic flashtube or a photoflash lamp as both the light source and the shutter for...
relief
The discernment of depth or apparent difference in distance that causes the object to stand out from its background because...
image comparison
A method used in imaging to detect subtle differences between two apparently similar pictures. It can be achieved by...
light frame
The term for an image captured by a detector and from which a dark frame, bias frame and/or flat-field frame can be...
spectrum measuring instrument
A traveling microscope or an automatic microdensitometer used to measure the spectrum plate obtained in a spectrograph.
flash radiography
A technique used in radiography to obtain an unblurred image of a moving object by the use of very short x-ray exposures,...
focus control
1. A mechanism that permits the focusing of an optical system.2. A means of obtaining the sharpest image from a cathode-ray...
light filament
Phenomenon caused by an ultrashort and ultra-intense light pulse propagating in a Kerr medium, such as air or water. When...
visual angle
The angle subtended by an object at the point of observation.
angular subtense
The measured planar or solid angle of related aspects of an optical system with respect to an optical axis.
silver-disc pyrheliometer
An instrument that uses a blackened silver-disc reflector with a shutter to create temperature fluctuations that are...
FTIR spectrometer
FTIR (Fourier transform infrared) spectrometer is a powerful analytical instrument used to obtain an infrared spectrum of...
apparent field
The angular subtense of the field of view in the image space of a telescope, as differentiated from that in the object space...
Polarization Imaging
A subsurface imaging technique based upon the polarization of light reflected off an object. The polarization of reflected...
sun-tracking concentrator
Controlled beam technology that introduces beams of sunlight through holes in a roof that are relayed throughout the...
holographic particle velocimetry
A method of measuring flow velocity by seeding the flow with neutrally buoyant particles and using a pulsed laser to...
photogrammetry
Photogrammetry is a technique used to obtain accurate three-dimensional measurements of objects and environments through the...
point light source
1. With respect to angular subtense, a source of light, such as a star, that is very small. In a lab, a point source may be...
clinical photography
The application of photography, with the exception of radiography, to obtain pictures of parts or the whole of a patient to...
multiple lens camera
A camera that uses a rotating mirror to project sequential images onto lenses that are arranged in an arc. The reflected...
multiple invariance
Characteristic of optical correlators in which invariance to more than one distortion parameter per axis of the processor is...
aerial camera
Camera designed for the imaging of the earth's surface in order to obtain high quality aerial images
radioactive tracer
A radioactive element that is placed or injected into a system to obtain an autoradiogram of the system. It is used in a...
terahertz spectrometer
A terahertz spectrometer is a scientific instrument used to measure and analyze the properties of materials in the terahertz...
scanning moire topography
A contour mapping technique that uses electronic scanning and sampling techniques instead of a reference grating (see moire...
pseudohologram
Coded image obtained optically with a nonredundant pinhole array imaging aperture.
photographic photometry
A form of photometric measurement, often used with light sources that are transparent or fluctuating, in which a...
color scanner
An instrument that uses a beam of light to scan a color transparency, and three differently filtered photosensors to record...
Fresnel diffraction
1. Also known as near-field diffraction. The field of radiation sent through an aperture in an absorbing screen at large...
ophthalmic photography
The methods and techniques used to obtain medical photographs of the human eye. To photograph the exterior of the eye,...
surface-enhanced Raman scattering
Surface-enhanced Raman scattering (SERS) is a powerful analytical technique that enhances the Raman scattering signal of...
microstereology
Microscopic investigation of two-dimensional areas of a three-dimensional object that can be quantitatively evaluated by...
additive color process
A process of color photography in which colors are added one to another in the form of light, rather than as colorants, to...
polychromatic acousto-optic modulator
A crystal-based device that combines and adjusts the intensities of multiple wavelengths of laser light in order to obtain...
hyperspectral imaging
Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the...
fiber optic window
The face of a cathode-ray tube (CRT) that has a fiber optic sheet attached to its surface. The sheet's fibers are at right...
autofluorescence
Autofluorescence refers to the natural emission of fluorescence exhibited by certain biological structures or molecules when...
image subtraction
A method used to compare two pictures of the same subject taken at different times. See image comparison.
digital subtraction
The process by which the values of one digital image of an object or scene are removed from a second slightly different...
instantaneous field of view
Instantaneous field of view (iFOV) is a term commonly used in the context of remote sensing, imaging systems, and optical...
endoscope
An endoscope is a medical device used for visualizing and examining the interior of hollow organs, body cavities, or...
gain-switching
Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium....
automated optical inspection
Automated optical inspection (AOI) is a technology used in manufacturing processes, particularly in electronics, to...
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...
fiber optic spectrometer
A fiber optic spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to...
limiting angular subtense (amin)
The apparent visual angle that divides intrabeam viewing from extended-source viewing.
Raman spectroscopy
Raman spectroscopy is a technique used in analytical chemistry and physics to study vibrational, rotational, and other...
metabolic imaging
Metabolic imaging refers to the visualization and quantification of metabolic processes within living organisms, tissues, or...
spectroheliograph
An instrument in which an image of the sun is scanned by the entrance slit of a monochromator, the exit slit simultaneously...
cesium-antimonide photocathode
A photocathode that exhibits maximum sensitivity in the blue and ultraviolet regions of the spectrum. The sensitivity is...
reflected ultraviolet photography
A photographic method used to obtain an image of a subject by means of its reflectance of incident ultraviolet radiation. An...
Jacquinot advantage
The higher throughput obtained with an FTIR device compared with traditional spectrometers that need slits to achieve...
monomer exchange diffusion
Process that occurs when a polymerized soft plastic rod with higher refractive index is placed in a bath of a lower...
laser-induced fluorescence
Laser-induced fluorescence (LIF) is a spectroscopic technique that involves using a laser to excite molecules or atoms,...
laser frequency measurement
Mod Method of obtaining precise temporal mode characteristics.
apparent visual angle
The angle subtended by an object, determined by the size of the object and its distance from the viewer.
differential interference contrast microscopy
Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast microscopy, is an optical...
Canada balsam
A resin obtained from the balsam fir, Abies balsamea, used as a lens cement.
bilinear interpolation
It is often necessary to estimate the value of what a pixel would be between neighboring pixels. This is accomplished by...
subtractive color process
The basic process of color photography whereby colors are subtracted from white light by means of filters, making all colors...
scanning electron microscopy
Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution,...
steradian
The unit solid angle subtended at the center of a sphere by an area on its surface equivalent to the square of the radius;...
optical coherence tomography imaging system
Optical coherence tomography (OCT) is an imaging technique used in medical diagnostics and biomedical research to obtain...
image storage panel
A modified form of an image-retaining panel that can be used in subdued daylight. This is achieved by adding a layer of zinc...
body
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...
spectral domain optical coherence tomography
Spectral domain optical coherence tomography is an imaging technique used in medical diagnostics, particularly in...
dye transfer method
The subtractive imbibing process of transferring color prints on paper whereby the dyes from three separately prepared...
coherence length
That length over which energy in two separate waves remains constant. With respect to a laser, the greatest distance between...
Snellen letter
The letter form used on visual performance test charts. The overall letter height is equal to five times the thickness of...
partial coherence theory
Totally coherent radiation is produced by a purely monochromatic point source. In the real world the energy will have a...
probe
Acronym for profile resolution obtained by excitation. In its simplest form, probe involves the overlap of two...
histology
Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs...
metallic mesh filter
An interference filter in which a very thin metal foil with a periodic array of square holes (inductive mesh) or a thin...
video subtractor
Lovibond tintometer
A subtractive colorimeter that expresses a liquid's or object's color as a combination of three colors. These colors are...
depth of field
The distance, on either side of the object plane focused on, through which satisfactory image definition can be obtained....
time domain
The time domain is a concept used in signal processing and analysis to describe signals in terms of their behavior over...
hyperspectral imaging camera
A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide...
erect image
An image, real or virtual, whose spatial orientation is identical to that of the object. The image obtained at the retina...
planar access coupler
Low-insertion-loss fiber coupler fabricated from a sheet of light-sensitive material laminated onto a fused quartz substrate...
optical resolution
A measure of image quality produced by an optical system. May be specified in terms of cycles per millimeter, referencing a...
Shack-Hartmann wavefront sensor
The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system....
adaptive optics
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of...
center of perspective
That viewpoint at which the angular subtenses of points in the picture are identical to angular subtenses of the original...
laser oscillator
Contains the light or beam path within a laser device. The oscillator uses reflective optical components that are oriented...
point cloud
A point cloud is a set of data points in a three-dimensional coordinate system, where each point represents a specific...
pulsed-dye laser
A laser with a gain medium consisting of an organic dye, which is carbon-based. The dye is mixed with a solvent, allowing...
Fabry-Perot cavity
An optical resonator in which feedback is accomplished by two parallel planes. In diode lasers, the planes are obtained by...
pseudo-second-derivative
A method used to approximate the values of the homogeneous second derivatives at each iteration in the course of lens design...
parallactic angle
The angular difference in the direction of an object as seen from two points of observation. The angle subtended at the...
Weissenberg method
The Weissenberg method, named after the German physicist Karl Weissenberg, is a technique used in x-ray crystallography for...
quantitative phase imaging
Quantitative phase imaging (QPI) is an advanced imaging technique used in microscopy to measure and analyze the optical...
minimum perceptible
The smallest object that may be seen, measured in terms of the angle subtended by the object measured at the eye. Also...
subtractive colors
Cyan, magenta and yellow. They are called subtractive because they each subtract one color by absorbtion and reflect the two...
perspective distortion
The distortion that is the result of viewing a print from a point other than the center of perspective. The center of...
underwater television system
A television system designed to obtain pictures of objects or scenes beneath the surface of the water. Generally, a...
Sonnar lens
A photographic objective that uses the thick meniscus principle to obtain its power. It is designed to photograph small...
modulation bandwidth
The highest frequency at which a laser diode can be driven and still be modulated acceptably that further results in the...
stellar parallax
The angle subtended by the mean distance of the Earth from the sun at the distance of a given star from the sun.
additive manufacturing
Additive manufacturing (AM), also known as 3D printing, is a manufacturing process that involves creating three-dimensional...
photoacoustic spectroscopy
A method for obtaining the optical absorption spectra of solids, semisolids, liquids and gases. PAS is inherently...
compound crosspoint
A device for obtaining very low crosstalk in a crosspoint by arranging two simple switches along different arms of a passive...
reflection x-ray microscopy
A means of high resolution study through the application of soft and hard x-rays onto a sample surface in order to obtain...
overscanning
In a cathode-ray tube, the deflection of the beam of the tube over an angle that surpasses the angle that subtends the...
filter kernal
A function used in a convolution filtering operation. The image to be filtered is convolved with the filtering kernel to...
moiré deflectometry
An optical interference technique widely utilized as a method of nondestructive testing when determining the ray deflection...
limiting angle of resolution
The angle subtended by two points or lines that are just far enough apart to be distinguished as separate. The ability of an...
orange peel
In the context of imaging, particularly digital imaging and printing, "orange peel" refers to a texture or visual distortion...
holographic tomography
Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional...
radial distribution method
A statistical analysis of facts obtained when the intensity of x-ray diffraction is calculated at different angles. In this...
swept-source laser
A swept-source laser, also known as a wavelength-swept laser, is a type of laser that rapidly and continuously changes its...
spectroscopy
Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves...
spectral repeatability
Spectral repeatability refers to the consistency and reproducibility of spectral measurements across multiple trials or...
correlated double sampling
A technique for removing thermal noise and drift from focal plane assemblies by sampling the system output between views of...
x-ray diffraction
The bending of x-rays by the regular layers of molecules in a crystal acting like a very small diffraction grating. The...
focus
1. The focal point. 2. To adjust the eyepiece or objective of a telescope so that the image is clearly seen by the observer....
hyperspectral resolution
Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a...
attenuated total reflectance spectroscopy
Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples....
color perception test equipment
Equipment for testing an observer's color vision. Some tests require the identification or ordering of colored samples. The...
Felgett advantage
The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds...
speckle imaging
A technique for obtaining improved resolution of images produced by large telescopes and distorted by the effects of...
minimum separable
The least space between two parallel lines that can be discriminated as a gap to the human eye. It is measured in terms of...
gray-scale modification
Image enhancement operations that involve altering gray-scale values. For instance, brightness sliding involves adding or...
ratiometry
Ratiometry is a technique used in various scientific fields, particularly in analytical chemistry and biochemistry, to...
powder radiography
A technique used in radiography to determine a crystal's structure by obtaining radiographs of it in powder form, normally...
angular spectrum approach
The angular spectrum approach is a mathematical and computational technique used in the field of optics to analyze and...

(142 results found)

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