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AST Dictionary Terms

replica grating
A reproduction made of an original grating -- usually by casting thermosetting plastics onto the original -- to avoid the high expense of making the original gratings.
dichroic polarizer
A polarizer that consists of dichroic polarizing material embedded in a plastic sheet, and that transmits light that is...
flow chemistry
Flow chemistry, also known as continuous-flow chemistry, is a chemical manufacturing process where reactions take place in a...
Vegard-Kaplan bands
The bands found by Vegard in the spectrum of the aurora borealis and by Kaplan in the nitrogen afterglow. They are formed by...
lens blank
A lens blank is a piece of optical material in a raw, unfinished state, typically in the form of a disk or block, from which...
b integral
Calculates the exponential growth of the least stable spatial frequency in a laser beam, and is the numerical equivalent of...
high dynamic range
High dynamic range (HDR) refers to a technology that allows for a broader and more dynamic range of luminosity in visual...
Petzval surface
A paraboloidal surface on which the image is located when there is no astigmatism.
replicated optics
Optical components, usually reflectors, produced using proprietary techniques that transfer the precision of a master to a...
thermophotovoltaic
Thermophotovoltaic (TPV) refers to a technology that converts heat energy into electricity using the principles of...
ophthalmology
Ophthalmology is a branch of medicine that focuses on the anatomy, physiology, and diseases of the eyes and visual system....
excitation index
The ratio of the intensities of two specified spectral lines of a source having vastly different excitation energies. This...
stochastic optical reconstruction microscopy
Stochastic optical reconstruction microscopy (STORM) is a superresolution microscopy technique that enables imaging of...
photomultiplier tube
A photomultiplier tube (PMT) is a highly sensitive vacuum tube that detects and amplifies low levels of light. It is widely...
astronomical scintillation
Any irregular motion, variation in intensity or change in color that arises because of atmospheric turbulence during the...
plastic polishing
Polishing with a plastic pad.
custom lapping and polishing services
Custom lapping and polishing services involve specialized processes used to improve the surface finish and dimensional...
astrometry
The analysis and measurement of celestial bodies, their motions and positions.
magnetorheological finishing
Magnetorheological finishing (MRF) is a precision optics polishing technique used for shaping and finishing optical surfaces...
PIN photodiode
A PIN photodiode is a type of photodetector or semiconductor device used to convert light signals into electrical signals....
plastic optical fiber
Plastic optical fiber (POF) is a type of optical fiber made from transparent plastic, typically polymethylmethacrylate...
polished mold
A mold for glass or plastics often made of stainless steel to prevent pitting or oxidation in service. It is polished to the...
panoramic camera
A camera designed to form a continuous record of an expansive section of the horizon. The typical panoramic camera is...
circle of least confusion
Best point of focus for an image in a beam of light at the smallest cross section of the beam.
astronomical camera
A camera designed to record astronomical objects (e.g., stars, planets, nebulae, galaxies) and their spectra.
endoscope
An endoscope is a medical device used for visualizing and examining the interior of hollow organs, body cavities, or...
plastic fiber
Fiber in which both core and cladding are made of plastic.
excimer laser
An excimer laser is a type of ultraviolet laser that emits short pulses of light in the ultraviolet spectrum. The term...
profile dispersion
In an optical waveguide, that dispersion attributable to the variation of refractive index profile with wavelength. The...
optical filter
An optical filter is a device that selectively transmits or blocks specific wavelengths, or colors, of light. Optical...
image orthicon
A camera tube widely used in television broadcasting. It consists of three sections within a single vacuum envelope. 1. A...
ring-laser gyroscope
A ring laser gyroscope (RLG) is a type of gyroscope that uses laser light to detect and measure changes in orientation. It...
tessar lens
A lens similar to the Cooke triplet anastigmat, with the rear crown achromatized for improved coverage and definition. It is...
gravitational lens
The effect of a powerful gravitational field on light traveling through the field. This effect is detectable in astronomical...
astronomical mirror
An astronomical mirror, also known as a telescope mirror or primary mirror, is a key component of a reflecting telescope. It...
raster scan display
A display in which regeneration takes place serially at a fixed speed in a set pattern through the scan lines.
fast Fourier transform
threshold contrast
In visual perception, the smallest difference in illumination perceived on the average.
quantum entanglement
Quantum entanglement is a phenomenon in quantum mechanics where two or more particles become correlated to such an extent...
histology
Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs...
astigmatizer
A cylindrical lens that may be rotated to distort a bundle of light originating at a point source, to form a line image.
isochromatic lines
1. Lines of the same color. 2. A term used in photoelastic stress analysis to refer to the interference fringes produced in...
anisotropic
Anisotropic is a term used to describe a material or substance that exhibits different properties or behaviors in different...
swept source optical coherence tomography
Swept-source optical coherence tomography is an imaging technique used in medical diagnostics, particularly in...
Nomarski microscopy
Also referred to as differential interference contrast (DIC) microscopy; Nomarski microscopy is a unique form of microscopy...
microfilm camera
A camera used to reduce originals onto film for easy storage. There are two basic types: one in which the film is fixed...
machine vision lens
A machine vision lens is a specialized optical lens designed for use in machine vision systems, which are used for automated...
quasar
A contraction of quasi stellar. An astronomical object that appears to be a star but has a different, larger redshift.
additive manufacturing
Additive manufacturing (AM), also known as 3D printing, is a manufacturing process that involves creating three-dimensional...
thermoplastic material
 reflectance confocal microscopy
Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that allows for high-resolution, in vivo imaging...
differential interference contrast microscopy
Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast microscopy, is an optical...
television bandwidth
The span of frequencies within which a single channel of broadcast television must fall; in the US, it is 6 MHz.
interphako interference microscopy
Measures the refractive indices axially from the fiber profile. Microscopy technique provides an interferogram with high...
quantum
The term quantum refers to the fundamental unit or discrete amount of a physical quantity involved in interactions at the...
emission spectrum
An emission spectrum is a graphical representation or a characteristic pattern of the wavelengths or frequencies of light...
point processing
In digital image processing, a subcategory of frame processing that transforms pixel brightness and contrast through use of...
pixel
A pixel, short for "picture element," is the smallest controllable element of a digital image or display. It is a...
optical encoder
A device designed to measure linear or rotary motion by detection of the movement of markings on a transparent medium past a...
digital camera
A digital camera is a device that captures and records still images or video in digital format. Unlike traditional film...
contrast transfer function
astronomical observatory
A facility designed for the observation and recording of astronomical phenomena.
spectrosensitometer
A sensitometer having a continuously controlled monochromator to measure spectral sensitivity and contrast of photographic...
imbedding material
A thermoplastic or thermosetting material used to hold an object fixed and keep it from deterioration. In microcircuitry,...
spurious resolution
A phenomenon that causes the details in an image to appear at a spatial frequency higher than that at which the contrast...
quantitative phase imaging
Quantitative phase imaging (QPI) is an advanced imaging technique used in microscopy to measure and analyze the optical...
hard coating
Usually a dielectric coating on glass or plastic optics; a coating that is comparable in hardness to glass itself.
frame
1. To center an image or place it in any part of the television screen desired. Also applies to stills. 2. A single image of...
halide
In chemistry, a halide refers to a chemical compound containing one or more halogen atoms bonded to another element. The...
grinding tool
A tool of cast iron or another suitable medium used with a slurry of silicon carbide, aluminum oxide or emery for grinding...
Mie scattering
Mie scattering, named after the German physicist Gustav Mie, refers to the scattering of electromagnetic radiation (such as...
vertical resolution
In television system specifications, the number of parallel horizontal black and white lines of equal thickness, that can be...
virtual reality
Virtual reality (VR) is a computer-generated simulation of a three-dimensional environment or experience that can be...
integrated photonics
Integrated photonics is a field of study and technology that involves the integration of optical components, such as lasers,...
photoelasticity
The process of determining, with the aid of plane-polarized light, the stress distribution in materials under complex...
National Television Systems Committee
The code used to describe the United States system of color telecasting.
digital signal processing
Digital signal processing (DSP) refers to the manipulation and analysis of signals, which are representations of physical...
carbonization
Carbonization is a process in which organic materials are heated in the absence of air, leading to the decomposition of the...
penumbra
A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts:...
CCD camera
A CCD camera, or charge-coupled device camera, is a type of digital camera that utilizes a CCD image sensor to capture and...
scanning electron microscopy
Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution,...
mode-locked lasers
Mode-locking is a technique used in lasers to produce ultrashort pulses of light with durations on the order of picoseconds,...
rotating mirror scanner
Developed for use in military reconnaissance systems, it consists of a polygonal mirror, drive motor, interface between...
averted vision
In astronomy, the method of deliberately viewing objects with peripheral vision to take advantage of the eye's greater...
lab-on-a-chip
A lab-on-a-chip (LOC) is a miniaturized device that integrates various laboratory functions and capabilities onto a single,...
optical materials
Optical materials refer to substances or compounds specifically chosen for their optical properties and used in the...
Fresnel lens
A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin...
remote sensing
Remote sensing is a method of data collection and observation where information about objects, areas, or phenomena on...
aplanatic points
Aplanatic points refer to specific points in an optical system where certain aberrations, such as spherical aberration or...
surface-enhanced Raman spectroscopy
Surface-enhanced Raman spectroscopy (SERS) is an analytical technique that combines the principles of Raman spectroscopy...
photopolymer hologram
A holographic plate coated by photopolymeric mixtures that are composed of one or more monomers and a photoredox catalyst...
hard elastics
High-modulus elastic fibers that exhibit the following differences from conventional elastic fibers: Increasing temperature...
allyl diglycol carbonate
Commonly known as CR39, this thermosetting plastic is used in the casting of eyeglass lenses because of its toughness and...
stable multipass Fabry-Perot interferometer
A plane-parallel interferometer that yields extremely high contrast over a wide range of finesse values without...
graser
An acronym of gamma ray amplification by stimulated emission of radiation. It is a gamma ray laser that operates between...
linear plastic
A term for thermoplastic optical materials; that is, those in which the polymer chains remain linear after heating and...
microfluidics
Microfluidics is a multidisciplinary field that involves the manipulation and control of very small fluid volumes, typically...
half-shade device
A device for forming at least two adjacent areas of polarized light. The angle between the directions of vibration of the...
thermoplastic recording device
A display device having a thermoplastic film as the control layer medium. The film, moving from a playoff reel, is scanned...
3D printing
3D printing, also known as additive manufacturing (AM), is a manufacturing process that builds three-dimensional objects...
spatial resolution
Spatial resolution refers to the level of detail or granularity in an image or a spatial dataset. It is a measure of the...
eye guard
A shield of rubber, plastic or metal used to protect the eyes of the observer from stray light and wind, and to maintain the...
direct-vision pocket spectroscope
A small handheld instrument consisting of a slit and collimator that feeds light into a small direct-vision dispersing...
chemical vapor deposition equipment
Chemical vapor deposition (CVD) equipment refers to a class of specialized apparatus used in the process of chemical vapor...
particle acceleration
Particle acceleration refers to the process by which charged particles, such as electrons or protons, gain kinetic energy...
holographic tomography
Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional...
redshift
The displacement of spectrum lines, as determined by the increasing distance between, and the relative velocity of, the...
laser crystal
A laser crystal, also known as an active medium or gain medium, is a solid-state material used in the construction of...
Baker corrector
A two-mirror corrector for a parabolic primary mirror that provides anastigmatic performance for large astronomical...
temporal Fourier hologram
A technique used to suppress extreme noise amplification during digital image reconstruction that relies on smoothing and...
Keplerian astronomical telescope
A simple form of astronomical telescope that uses a fixed objective and a focusable eyepiece. The objective forms an...
Wollaston prism
A polarizing prism consisting of two calcite prisms cemented such that they deviate the two emerging beams (which are...
parallel scanning
Parallel scanning refers to a method of acquiring data or images simultaneously from multiple sources or in parallel, rather...
adaptive optics
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of...
Kerr effect
The Kerr effect, named after the physicist John Kerr who first observed it in 1875, is a nonlinear optical phenomenon where...
active-matrix OLED display
An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two...
astronomical spectrograph
An instrument that photographs the spectra of an extraterrestrial object.
Schmidt camera
A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the...
scanning electron microscope
A scanning electron microscope (SEM) is a powerful imaging instrument used in scientific research, materials...
laser optics
Laser optics refers to a broad category of optical components and systems designed for manipulating and controlling laser...
optical fiber optic switches
Optical fiber optic switches are devices used in optical fiber communication systems to selectively route optical signals...
fiber-linked array image formatter
A wide-field multiobject spectroscopy system used in astronomy, in which a bundle of low-loss optical fibers positioned on...
contrast control
With respect to television, a potentiometer that allows variation of the intensity of the different elements of an image and...
chuck
In the optical field, a tube to which a lens is fastened for centering.
source
A physical source of radiation, as contrasted to illuminant. See illuminant.
anastigmat
A compound lens combination whose astigmatic difference is zero for one or more off-axis zones in the image plane. In such a...
photoelastic
In optics, the double refraction that is produced when stress is applied to a transparent material. Plastics, which are...
Raman spectroscopy
Raman spectroscopy is a technique used in analytical chemistry and physics to study vibrational, rotational, and other...
autofluorescence
Autofluorescence refers to the natural emission of fluorescence exhibited by certain biological structures or molecules when...
photometry
Photometry is the branch of science that deals with the measurement of light, particularly in terms of its intensity and the...
selenology
That branch of astronomy concerned with the study of the moon's physical characteristics.
Kerr soliton
A Kerr soliton refers to a specific type of soliton, a self-reinforcing wave packet, that arises in nonlinear optical...
television line number
The value equal to the raster height divided by the half-period of a periodic test pattern.
point spread function
The point spread function (PSF) is a fundamental concept in imaging that describes the response of an imaging system to a...
optical gate
An optical gate typically refers to a device or system that controls the transmission of light, allowing it to pass through...
distance-luminosity relationship
In astronomy, the relation that states that the intensity of a star's visible radiation is inversely proportional to the...
substrate
A substrate refers to a material or surface upon which another material or process is applied or deposited. In various...
virtual retinal display
The use of miniature scanners to project raster-scanned video images directly onto the surface of the human retina,...
charge-coupled device
A charge-coupled device (CCD) is a type of electronic image sensor used in various imaging devices, including digital...
absolute purity threshold
Least value of color value combinations which gives white light; minimum purity as determined to be white.
edge contrast
modulation transfer function
Also called sine wave response and contrast transfer function. The modulation transfer function is the ratio of the...
laser marking
Laser marking is a process in which a laser beam is used to mark or engrave a surface by altering its properties or...
astigmatic difference
In an optical system having astigmatism, the distance between the tangential and sagittal image planes.
burn
A surface imperfection caused by a polisher running dry too long. It occurs with felt or plastic polishers, and may appear...
transversely excited atmosphere carbon dioxide laser
Abbreviated TEA CO2 laser. A gas laser that provides shorter pulses and higher peak powers than conventional CO2 lasers. The...
Sturm interval
The distance between two focal lines in an astigmatic image produced by a lens or mirror.
electrostatic tape camera
A camera that records its images electrostatically on plastic tape; used in situations where radiation would have an adverse...
binocular magnifier
A device having a pair of decentered lenses, one for each eye, that focuses on a single object as a magnifier. It is often...
sheet polarizer
A sheet of plastic material containing microscopic crystals of herapathite or some other similar substance that transmits...
astigmatic spectral line
In an astigmatic grating, the image of the entrance slit located at the primary focus.
cylindrical lens
A cylindrical lens is an optical component that has different curvatures along its two orthogonal axes, resulting in a shape...
optical microphone
Laser-powered telephone device for analog communications that employs a vibrating plastic membrane as a transmitter to...
ultraphotic rays
The rays (such as ultraviolet rays) lying past the visible region of the spectrum.
nonlinear optics
Nonlinear optics is a branch of optics that studies the optical phenomena that occur when intense light interacts with a...
light sheet fluorescence microscopy
Also known as single plane illumination microscopy (SPIM), this process was designed for imaging of sensitive samples and...
three-photon microscopy
Three-photon microscopy is an advanced imaging technique that belongs to the family of multi-photon microscopy methods. It...
translucent screen
A screen composed of a sheet of diffusing plastic material that reveals excellent image detail for close viewing. It is...
pulsar
An astronomical body that emits radiation concentrated by a strong magnetic field into two beams that rotate, giving a...
rolling shutter artifacts
Rolling shutter artifacts are distortions or visual anomalies that can occur in images or videos captured by cameras with...
fiber-coupled LED
A fiber-coupled LED (light-emitting diode) refers to an LED device that is optically coupled to an optical fiber for the...
diamond turning
Diamond turning, also known as diamond machining or diamond cutting, is a precision machining process used to produce...
high-index-contrast subwavelength grating
A superthin, highly reflective mirror.
magnitude
In astronomy, the relative brightness of a celestial body. Originally a scale from 1 to 6, where 1 represented the brightest...
thin-film solar cell
A solar cell that is lightweight and flexible because of its construction by vacuum deposition of a semiconductor material...
modulation
In general, changes in one oscillation signal caused by another, such as amplitude or frequency modulation in radio which...
image working distance
The distance between the last vertex of a lens and the image.
oblique error
The image error that results from astigmatism, coma, oblique spherical aberration, lateral color and distortion.
integration time
Integration time, in the context of optics, imaging systems, and sensor technology, refers to the duration over which a...
Photoelastic equipment and supplies
Photoelastic equipment and supplies refer to instruments and materials used in photoelasticity, a technique used to analyze...
Kerr cell
A cell filled with a transparent material that, when placed in a strong electrical field, exhibits double refraction. Since...
saturation
1. The decrease of the absorption (or gain) coefficient of a medium near some transition frequency when the power of the...
monomer exchange diffusion
Process that occurs when a polymerized soft plastic rod with higher refractive index is placed in a bath of a lower...
electron multiplication charge-coupled device camera
An EMCCD (electron-multiplying charge-coupled device) camera is a type of scientific camera specifically designed for...
gallium nitride
Gallium nitride (GaN) is a compound made up of gallium (Ga) and nitrogen (N). It is a wide-bandgap semiconductor material...
linear image sensor
A linear image sensor is a type of solid-state electronic device used to capture and convert light into electrical signals....
detector array
A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format....
brightfield
Brightfield refers to a type of microscopy and imaging technique in which the specimen is illuminated with a white light...
diffraction grating
A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel...
plastic-clad silica fiber
An optical waveguide having a silica core and a plastic cladding.
acetone
Optic surface cleaning liquid that may be applied to glass, crystal, dielectric and metal surfaces; however, may not be...
nanoparticle photonic resonator absorption microscopy
Nanoparticle photonic resonator absorption microscopy is a microscopy technique that combines the principles of photonic...
television transmitter
An electronic device used to encode video and audio signals of a television camera into radio waves that are broadcast to...
lateral shearing interferometer
A lateral shearing interferometer is an optical device used in interferometry to measure phase differences between two beams...
terahertz
Terahertz (THz) refers to a unit of frequency in the electromagnetic spectrum, denoting waves with frequencies between 0.1...
MSM photodiode
A metal-semiconductor-metal (MSM) photodiode is a type of photodetector that consists of metal electrodes on a semiconductor...
microchannel plate
A microchannel plate (MCP) is a specialized electron multiplier device used in various applications such as particle...
step-and-repeat printer
A projection printer that is capable of reproducing a multiplicity of images from a master transparency on a single support...
vidicon
A small television tube originally developed for closed-circuit television. It is about 1 inch in diameter and 5 inches...
Ti:sapphire laser
A Ti:sapphire laser is a type of solid-state laser that utilizes a titanium-doped sapphire crystal as the gain medium. The...
blocking shaper
A convex, concave or flat cast iron form that is used to shape a soft mold block of optical components.
plastic jackets
The direct cladding used for fused silica cores to create large numerical aperture fibers and used as overcoats to...
diamond-turned optic
Diamond turning refers to a precision machining process used to produce complex optical components, particularly lenses and...
blanking
The process by which the raster beam in a video tube is cut off during the retracing and sync periods.
raster unit
The vertical or horizontal distance between two addressable points on a display screen; indicates the basic resolution...
fiber bundle
A rigid or flexible, concentrated assembly of glass or plastic fibers used to transmit optical images or light. See aligned...
single-photon avalanche diode
A single-photon avalanche diode (SPAD) is a specialized type of photodetector designed to detect extremely weak optical...
Aston dark space
In the discharge of a vacuum tube, the narrow, nonluminous region that sometimes may be found between the cathode and its...
ray tracing
Ray tracing is a rendering technique used in computer graphics to simulate the way light interacts with objects in a scene....
atmospheric refraction correlation
Formulaic compensation to correct laser ranging data for the effects of horizontal refractivity gradients; it requires the...
astronomy
The scientific observation of celestial radiation that has reached the vicinity of Earth, and the interpretation of these...
modulator
A modulator is a device or component that modifies a carrier signal in order to encode information for transmission over a...
frequency domain
The frequency domain is a concept used in signal processing and analysis to represent signals and data in terms of their...
aspheric lens
An aspheric lens is a type of lens whose surface profiles deviate from the traditional spherical shape. Unlike spherical...
incoherent
In optics, the term denoting the lack of a fixed phase relationship between two waves. If two incoherent waves are...
nanotechnology
The use of atoms, molecules and molecular-scale structures to enhance existing technology and develop new materials and...
objective prism
1. A prism used in some instruments to bend light 90° before it enters the objective. 2. A dispersing prism located in...
digital twin
A digital twin refers to a virtual representation or digital counterpart of a physical object, system, or process. This...
structural color
Structural color refers to coloration in materials that is not caused by pigments or dyes but is instead a result of the...
intensified charge-coupled device camera
An intensified charge-coupled device (ICCD) camera is an advanced imaging device that combines the capabilities of both an...
photographic shutter efficiency
A measure of the total light passed by a shutter during an exposure, compared with the light that could be passed by an...
Fermat's principle
The principle that a light ray extending from one point to another will, after any number of reflections and refractions,...
random access multiphoton microscopy
Also known as RAMP microscopy, random access multiphoton microscopy is a microscopic technique that uses multiple...
refracting sphere
A transparent sphere that has an index of refraction that is different from that of the medium surrounding it; used in...
sidereal time
Frequently used in astronomical measurement, it is based on the diurnal rotation of a star relative to the fixed stellar...
superelastic collision
Observed phenomenon in laser pulses in which a large number of excited electrons are created and in which multiphoton...
catastrophic optical damage
The darkening of the laser facet of a semiconductor laser diode. It can be prevented by placing the component in a...
Mach bands
The illusory appearance of a light or dark band at a line of brightness contrast that enhances the edge between the two...
equidensitometry
1. The use of an electronic microdensitometer to measure points of equal density on a photographic deposit. 2. A technique...
chirped-pulse amplification
Chirped pulse amplification (CPA) is a technique used in laser physics to amplify ultrashort laser pulses to high energies...
ring blocking
The formation of a block by attaching optical elements to a plate with a ring of pitch or other thermoplastic material.
spectral bandwidth
The wavelength interval in which radiant intensity is at least 50 percent of the maximum spectral value.
polymer
Polymers are large molecules composed of repeating structural units called monomers. These monomers are chemically bonded...
harmonic generation
Harmonic generation refers to a nonlinear optical process in which incoming photons interact with a material and produce new...
radial astigmatism
The astigmatism in a lens system that results when light enters the system at an oblique angle.
confocal scanning microscope
A microscope design that involves apertures inserted in conjugate plane positions inside the microscope, with one aperture...
MEMS fiber optic switch
A MEMS fiber optic switch is a microelectromechanical system (MEMS) device designed to selectively route optical signals...
reflection grating
A reflection grating is an optical component that consists of a series of closely spaced, parallel reflecting surfaces or...
Zernike's phase contrast method
The introduction of a filter into an imaging system to implement a phase contrast for an intensity mapping of a pure phase...
Christiansen-effect filter
A transparent powdered solid immersed in a liquid or plastic of similar refractive index but widely different dispersion;...
apochromat
An apochromat, often referred to as an apochromatic lens or apochromatic objective, is a type of optical system designed to...
injection locking
The use of two lasers as a master-slave pair in order to control frequency and prevent chirp. When light from the master is...
spectrometer mask
A high-contrast transparency of the gas sought, or an array of exit slits that correlates with some features of the...
attosecond-pump attosecond-probe spectroscopy
Attosecond-pump attosecond-probe spectroscopy (APAP) is an advanced technique in ultrafast spectroscopy that allows...
emergent ray
In optics, the light ray leaving a medium in contrast to the entering or incident ray.
crystalline lens
The internal lens of the eye. It is semielastic to permit changes in its power when focusing on objects at near distances.
fractional photothermolysis
A laser skin-resurfacing method that creates microscopic thermal wounds referred to as microscopic treatment zones (MTZs),...
astronomical spectroscopy
The process of using a spectrograph with a telescope to acquire information on an astronomical object's speed and physical...
Shack-Hartmann wavefront sensor
The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system....
negative crystal
A uniaxial, birefringent crystal such as calcite or ruby in which the velocity of the extraordinary ray surpasses that of...
CMOS image sensor
A CMOS image sensor, short for complementary metal-oxide-semiconductor image sensor, is a type of semiconductor device used...
cross wire
Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects...
light-emitting diode
An LED, or light emitting diode, is a semiconductor device that emits light when an electric current passes through it. LEDs...
high-speed photography
Photography involving the recording of events that occur too fast to be perceived by the human eye or recorded by...
scientific CMOS camera
A scientific CMOS (complementary metal-oxide-semiconductor) camera is a type of digital camera specifically designed for...
mid-infrared camera
A mid-infrared camera is a type of imaging device designed to capture images in the mid-infrared (mid-IR) spectral range,...
internet of things
The internet of things (IoT) refers to a network of interconnected physical devices, vehicles, appliances, and other objects...
nonlinear scattering
Direct conversion of a photon from one wavelength to a lower energy photon of another wavelength(s) due to inelastic...
colorimeter
A colorimeter is a device used to measure and quantify the color characteristics of an object or a light source. It provides...
flexible display
A flexible display refers to a type of electronic visual display that is designed to be bendable, foldable, or rollable,...
contrast threshold
That contrast level that exists between two areas whose difference in brightness is just perceivable.
scopometer
A device used to take turbidimetric or nephelometric measurements by considering the contrast between a constant brightness...
injection seeding
The use of a small ultrastable master oscillator (a diode-pumped Nd:YAG laser) to achieve single-frequency operation of a...
optical cements and adhesive
Optical cements and adhesives are specialized materials used in the assembly and bonding of optical components in optical...
dichroic coating
A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively...
embossed hologram
A hologram imprinted on plastic or another medium; e.g., those commonly found on credit cards.
infrared detector
An infrared detector is a device that is used to detect and measure infrared radiation, which lies beyond the visible...
moiré deflectometry
An optical interference technique widely utilized as a method of nondestructive testing when determining the ray deflection...
spectroradiometer
A spectroradiometer is a device used to measure the intensity of light at different wavelengths across the electromagnetic...
clear eye distance
In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.
phase screen
A phase screen, in the context of optics and wave optics, refers to a surface or medium that introduces a phase delay to an...
retroreflector
A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their...
microscopy
Microscopy is a scientific technique that involves the use of microscopes to observe and study objects that are too small to...
refractive index contrast
A measure of the relative difference in refractive index between two optical materials. Most commonly used in fiber optics...
infrared camera
An infrared camera, also known as a thermal imaging camera or IR camera, is a device that captures and visualizes the...
single molecule localization microscopy
Single molecule localization microscopy (SMLM) is a group of super-resolution microscopy techniques that surpass the...
point cloud
A point cloud is a set of data points in a three-dimensional coordinate system, where each point represents a specific...
riez photodiode
A photodiode having a conducting grid that covers the surface of the photodiode junction and intercepts and wastes some of...
autofocus system
A means of adjusting the sharpness of an image automatically, with a sensor for estimating distance or contrast and a drive...
vacuum chamber
A vacuum chamber is a sealed enclosure from which air and other gases are removed to create a low-pressure environment,...
automated optical inspection
Automated optical inspection (AOI) is a technology used in manufacturing processes, particularly in electronics, to...
aplanatic surface
An aplanatic surface is an optical surface that is specifically designed or shaped to minimize spherical aberration and...
transport theory approximations
Multiple scattering method used in biological analysis in which approximations yield simple, explicit solutions, at least...
supertwisted nematic phase
A form of liquid crystal in which the 90° twist of the twisted nematic phase has been increased to 180° or more,...
histochemical staining
Histochemical staining is a laboratory technique used in biology and medicine to visualize specific chemical components...
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...
radius tool
A metal device of convex or concave curvature to which lens castings or semifinished lenses are cemented with only their...
fast axis
In a birefringent material, the index of refraction varies with the direction of vibration of a lightwave. That direction...
optical phase distortion
Optical phase distortion refers to a phenomenon where the phase of an optical wavefront is altered as it propagates through...
telescope mount
The base used to hold an astronomical telescope. It may be either altazimuth, with horizontal and vertical axes of rotation,...
CubeSat
A CubeSat is a type of miniaturized satellite characterized by its standardized size and modular design. CubeSats are...
corner cube
A corner cube, also known as a corner reflector or retroreflector prism, is a type of optical device used to reflect light...
elastic scattering
Scattering caused by the interaction between ingoing and outgoing particles of the same type, with no loss of kinetic energy.
extensometer
1. A strainmeter capable of measuring the change in the relationship between two reference points, provided that the points...
Cassegrain lens system
A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola....
astronomical photography
The use of photographs to record astronomical objects and phenomena for purposes of physical observation and measurement of...
Wadsworth mounting
A system used for gratings that consists of a concave mirror, a grating and a plate holder mounted normal to the grating to...
plastic lens
A lens made from transparent plastic material. Lenses over 31/2 in. in diameter are usually machined, ground and polished....
phase annulus
A term for the ring-shaped stop in a phase contrast microscope. The phase annulus limits the amount of light that reaches...
in vitro
In vitro is a Latin term that translates to "in glass." In scientific contexts, particularly in biology and medicine, it...
Astrosital
A glass-ceramic material developed in Russia. Astrosital resembles Zerodur in terms of its ultralow thermal expansion. Other...
raster
The pattern of lines traced by rectilinear scanning in display systems.
kron camera
Astronomical detector consisting of a photocathode isolated from the target by a coin value from which electrons are focused...
high contrast
A term used to describe a photograph, film or television picture where the values for black and white areas are at or near...
Goldberg wedge
A neutral-colored gelatin wedge, cast between glass plates, that is used as an intensity scale in certain types of...
photochromic
Photochromic refers to a property exhibited by certain materials, typically organic compounds or dyes, which undergo...
pseudo-second-derivative
A method used to approximate the values of the homogeneous second derivatives at each iteration in the course of lens design...
elasto-optic effect
A change in the refractive index of an optical fiber caused by variation in the length of the fiber core in response to...
thermoplastic film
A type of holographic film widely used for industrial applications because it is inexpensive and erasable.
glass
A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or...
indium gallium arsenide camera
An InGaAs (indium gallium arsenide) camera is a type of imaging device that utilizes InGaAs sensors to capture images in the...
Rowland circle
The circle that contains the slit, grating and primary astigmatic focus of a concave diffraction grating.
shadowgraph
A method of demonstration or examination using a point source illumination without the use of any projection lens between...
optical blank
A casting consisting of an optical material molded into the desired geometry for grinding, polishing or, in the case of...
pencil beam
In astronomy, the main lobe of an antenna pattern that has a small angular extent in two mutually perpendicular directions....
laser rangefinder
A laser rangefinder is a device that uses laser technology to measure the distance between the device and a target. It...
metabolic imaging
Metabolic imaging refers to the visualization and quantification of metabolic processes within living organisms, tissues, or...
galvanometric scanner
A galvanometric scanner, also known as a galvanometer scanner or galvo scanner, is a type of optical scanning device used to...
indium
Metal used in components of the crystalline semiconductor alloys indium gallium arsenide (InGaAs), indium gallium arsenide...
halogen
Any of the five elements astatine, chlorine, fluorine, bromine and iodine, grouped because their chemical properties are...
polling
Inquiry made to gain access by a master station in a token ring network.
least circle of confusion
The circle of confusion is a defocused or aberrated image of a point. Focus is generally set where the diameter of this...
femtosecond laser
A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds,...
overhead projector
A projector used to project transparencies. A horizontal 8 x 10-in. stage for writing or laying down preformed...
compression molding
A method of producing large volumes of plastic optical components in which powdered or sheet plastic is pressed between...
hydrophilic
Hydrophilic is a term used to describe substances or materials that have an affinity for water. The word hydrophilic comes...
brightness control
The manual shifting bias control of a cathode-ray tube that determines both the average brightness and the contrast of a...
superresolution
Superresolution refers to the enhancement or improvement of the spatial resolution beyond the conventional limits imposed by...
gallium arsenide injection laser
A laser system consisting of a planar PN junction within a single crystal of gallium arsenide. The pair of parallel,...
GigE
GigE, short for gigabit Ethernet, refers to a standard for high-speed Ethernet communication, capable of transmitting data...
free-space optics
Free-space optics (FSO), also known as optical wireless communication or optical wireless networking, refers to the...
two-photon excited fluorescence
Two-photon excited fluorescence (TPEF) is a nonlinear optical method that allows imaging of biological cells and living...
interlaced
Describing the standard television method of raster scanning in which the image is the product of two fields, each of which...
blocking pitch
An adhesive used to affix optical elements to an approximately shaped body -- usually of cast iron.
attosecond photonics sources
Attosecond photonics sources refer to devices or systems that generate extremely short pulses of light on the order of...
label-free
Label-free refers to a technique or method that does not require the use of additional labels, tags, or markers to detect or...
electrostriction
Elastic deformation of a dielectric caused by volume force when the dielectric is placed in an inhomogeneous electric field.
polystyrene
A plastic used in molded optical components. Styrene elements can be combined with acrylic elements to produce achromatic...
laser Q-spoiler
A fast-action shutter inserted between one end of a laser rod and the end mirror; when inserted to prevent emission and then...
optical air mass
A measure of the optical path length for light traveling from the sun or other celestial source through Earth's atmosphere...
optical power spectrum
Also known as the Wiener spectrum or the noise power spectrum, the optical power spectrum is a fundamental quantity in...
modulation transfer function analysis/measurement equipment
MTF analysis/measurement equipment refers to instruments and tools used to measure and analyze the modulation transfer...
laser welder
A system that uses the heat from a pulsed laser to weld metals. Because of the rapidity and localization in which the...
raster image processor
In imaging technology, a device that converts raster or line-scan data to pixel form for further processing.
photoelastic constant
A formulaic description of the linear change of the reciprocal optical dielectric tensor with either stress or strain.
holographic grating
A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists...
whole slide imaging
Whole slide imaging (WSI), also known as virtual slide microscopy or digital pathology, is a technology that involves the...
infrared
Infrared (IR) refers to the region of the electromagnetic spectrum with wavelengths longer than those of visible light, but...
pellicle mirror
A thin, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter, for...
phase contrast microscopy
Phase contrast microscopy is an optical microscopy technique that enhances the contrast of transparent and colorless...
convertible lens
Any lens with at least two lens elements, each of which can be used singly or in combined configurations.
lidar
Lidar, short for light detection and ranging, is a remote sensing technology that uses laser light to measure distances and...
active-matrix
An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two...
linear optics
Linear optics refers to the study and manipulation of light in a linear and deterministic manner, where the response of...
plastic optics
Plastic optics refers to optical components or systems that are made from transparent plastic materials, as opposed to...
image contrast
Also referred to as image visibility, the contrast of an image is the variation in the intensity of an image formed by an...
blocking tool
An instrument used to support optical parts to be cemented, or to be mounted in plaster.
pyramid error
Pyramid error in optics refers to an aberration in the shape of an optical surface, particularly in the context of mirrors....
ductility
A material's ability to undergo plastic deformation, specifically elongation, without fracturing.
frequency comb
A frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with...
compound semiconductor
A semiconductor made up of two or more elements, in contrast to those composed of a single element such as germanium or...
Golay cell
A thermal radiation detector consisting of a small cell with a blackened plastic front face that bulges slightly when heat...
low Earth orbit
Low Earth orbit (LEO) refers to a region in space that is relatively close to Earth's surface, typically characterized by...
ultraviolet microscopy
The study and photographing of microscope specimens in ultraviolet light; using an optical microscope containing fluorite...
toric lens
A lens having one or more toric surfaces. A toric surface is one having a maximum power in one meridian and a minimum power...
line-scan recording
A type of recording in which the recording line remains fixed and the recording medium is fed past the recording device.
contrast
The apparent difference in brightness between light and dark areas of an image. For a light target against a dark...
orthonormalization
Optimization method used in optical design computer programs that employs a variable-by-variable approach to construct new...
x-ray film
A film or plate that is usually coated on both sides with a very fast emulsion that is sensitive to x-rays, and used to...
broadband filter
A broadband filter is an electronic or electromagnetic device designed to pass a range of frequencies or signals within a...
cross-linked plastic
Plastic in which the polymer chains become irreversibly joined during molding. The cross-linking can be achieved by heating,...
anisotropy
Anisotropy refers to the property of exhibiting different values or characteristics when measured in different directions....
Marx generator
High-voltage, fast-discharge circuit named after its inventor, Erwin Marx. Its capacitors are charged in parallel and...
double-Gauss lens
A fast, wide-angle lens used in television and photographic cameras, with excellent overall correction, but subject to...
phase
In optics and photonics, "phase" refers to a property of electromagnetic waves, such as light, that describes the position...
scientific complementary metal-oxide semiconductor
Scientific complementary metal-oxide semiconductor (sCMOS) refers to a type of image sensor technology specifically designed...
radio astronomy
The detection and analysis of naturally formed extraterrestrial electromagnetic radiation within the radio frequency range...
optics
Optics is the branch of physics that studies the behavior and properties of light, including its interactions with matter...
phase-contrast generation
Microscopy technique to convert the phase structure of the wave transmitted or reflected by the specimen into a...
ultrasonic
Ultrasonic refers to sound waves with frequencies higher than the upper audible limit of human hearing, typically above...
digital holographic microscopy
Digital holographic microscopy (DHM) is an advanced imaging technique that combines holography and digital image processing...
photoacoustic imaging
Abbreviated PAI. An imaging modality with a hybrid technique based on the acoustic detection of optical absorption from...
telescope lens
A telescope lens is a primary optical component of a telescope system that gathers and focuses light to form an image. It is...
tempered glass
A glass that is heated, then chilled (usually by an air blast) to set up internal stresses so that the surfaces are under...
near-field scanning optical microscope
A scanning probe microscope that analyzes the surface of a specimen by recording the intensity of light as it is focused...
cladding
The low-refractive-index material that surrounds the core of an optical fiber to contain core light while protecting against...
birefringence
Birefringence is an optical property of certain materials that causes them to exhibit different refractive indices for light...
angular aperture
The angle between the most divergent rays that can pass through the lens to form an image. In a birefringent crystal light...
Koenig-Martens spectrophotometer
A visual, single-unit spectrophotometer with a biprism and a Wollaston prism. The Wollaston prism polarizes coincident...
luminous flux
Descriptive of the radiant power of visible light modified by the eye response. It is the measure of the flow of visible...
nematic phase
A form of liquid crystal with an appearance of moving, threadlike structures, particularly visible when observed in thick...
CMOS camera
A CMOS camera refers to an imaging device that employs a complementary metal-oxide-semiconductor (CMOS) image sensor to...
fiber optics
The use of thin flexible glass or plastic fibers as wave guides — or "light pipes" — to channel light from one...
magneto-optic shutter
A type of high-speed photographic shutter that uses Faraday rotation to produce exposure times as fast as 1 microsecond. It...
photoconductive antenna
Photoconductive antenna (PCA) is a semiconductor element that generates or detects high-frequency electromagnetic signals....
optical fiber
Optical fiber is a thin, flexible, transparent strand or filament made of glass or plastic used for transmitting light...
closed-circuit television system
A television system that does not broadcast television signals but transmits them over a closed circuit.
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...
field
1. In raster scan television, one of the two scans that are interlaced to make up a frame. 2. See field of view.
astigmatism
A lens aberration that results in the tangential and sagittal image planes being separated axially.
spectral domain optical coherence tomography
Spectral domain optical coherence tomography is an imaging technique used in medical diagnostics, particularly in...
Seidel aberrations
Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and...
acrylic
A thermoplastic or optically transmitting hard plastic produced by applying polymerization initiator and heat to a monomer.
time-correlated single photon counting
Time-correlated single photon counting (TCSPC) is a technique used in photon counting applications, particularly in the...
visual test chart
A series of high contrast block letters or similar objects arranged to permit the evaluation of eyesight in humans.
zero-order retarder
A quarter- or half-wave retarder made from two plates of quartz, mica or polymer with their fast axes crossed; the...
optical testing instrument
An optical testing instrument is a device or system used to evaluate and measure the performance, quality, and...
long-pass filter
A long-pass filter is an optical filter that allows longer wavelengths of light to pass through while blocking or...
continuous wave
Continuous wave (CW) refers to a type of signal or transmission where the signal is constant and does not vary with time. In...
sync
Abbreviation of "synchronization.'' In television, the timing signals used to drive the scanning process. Horizontal...
contrast filter
A filter designed to improve contrast in an imaging system. For visual and black and white photosystems, a yellow filter is...
neuromorphic vision sensor
A neuromorphic vision sensor is a type of imaging device designed to mimic the structure and functioning of the human visual...
chelate laser
A laser having a rare-earth chelate within a plastic host as the lasing material. The chelate laser is easily pumped and has...
thermoplastic cement
An adhesive whose viscosity decreases as the temperature is increased to a limit. Canada balsam, resin and pitch are...
remote inspection
Remote inspection refers to the process of inspecting, evaluating, or monitoring assets, equipment, infrastructure, or...
ultrashort-pulse laser
A laser capable of generating light pulses that last only a few femtoseconds. This can be achieved by nonlinear filtering to...
zero halogen thermoplastic
A highly flame-retardant material used to jacket fiber optic cables, especially on shipboard applications.
supercontinuum
Supercontinuum refers to a broad spectrum of light that spans a wide range of wavelengths, typically from the visible to the...
injection-mounted assembly
A process by which a plastic cell is molded around a glass lens or lenses to create a mount, eliminating the metal barrel...
chromatic aberration
Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a...
blown fiber
A technique developed by British Telecom in which the viscous drag of air is used to install optical fibers in narrow...
thermoset plastic
 azimuth angle
1. In astronomy, the angle measured clockwise (eastward) in a horizontal plane, usually from north (true north, Y-north,...
nonlinear optical materials
Nonlinear optical materials are substances that exhibit optical properties that are not linearly proportional to the...
fiber optic cable assembly
A fiber optic cable assembly refers to a complete unit consisting of optical fibers, connectors, protective jackets, and...
liquid crystal light valve
A liquid crystal light valve (LCLV), also known as a spatial light modulator (SLM), is an optical device that modulates the...
injection molding
A method of producing high-quality plastic optics in large volumes by injecting the heated, liquified plastic at high...
ultrafast pulsed laser
An ultrafast pulsed laser is a type of laser that emits extremely short pulses of light with durations typically on the...
line spectrum
A spectrum formed by radiation whose energy values of the property being measured cluster about at least one discrete value,...
near-infrared camera
A near-infrared (NIR) camera is an imaging device designed to capture images in the near-infrared region of the...
horizontal blanking interval
In television, the period during which the electron beam is cut off while the raster returns from the right-hand side of the...
spheric lens
A spheric lens, also known as a spherical lens, is a type of optical lens with at least one surface that is part of a...
machine vision lighting
Machine vision lighting refers to the use of specific lighting techniques and equipment in the field of machine vision,...
constant luminance encoder
A device used in broadcast CCD cameras to improve definition in heavily saturated colors by band-limiting the color...
photographic thermometry
The photographic recording of the heat radiation emitted from various points on the object as corresponding density...
Pellin-Broca prism
A form of dispersing prism, often used in monochromators, that consists of a common right-angle prism with a 30°...
ring topology
A system of local area networking in which each node or station is connected to two others, ultimately forming a loop. Data...
high-speed motion camera
A high-speed motion camera, also known as a high-speed camera or slow-motion camera, is a specialized imaging device...
image distance
The distance from the last surface of a lens system to the image. For a thin lens system, this distance is equivalent to the...
mounting cement
An adhesive used to hold optical components in their mounts. It may be a thermoplastic or chemical-hardening substance.
polycarbonate
A tough, durable, heat- and cold-resistant optical quality plastic used in injection-molded items such as streetlight...
interferometric modulator display
Interferometric modulator display (IMOD) is a type of display technology used in electronic devices, known for its energy...
spatial light modulator
A spatial light modulator (SLM) is an optical device that modulates or manipulates the amplitude, phase, or polarization of...
hydrogel
A hydrogel is a three-dimensional network of polymer chains that are hydrophilic, meaning they have a strong affinity for...
immersion liquid
Term synonymous with refractive index liquid, but related more to tank or chamber immersion of crystals, fibers, lenses,...
meniscus anastigmat
An anastigmatic lens with a thick meniscus construction that flattens the field and corrects chromatic and spherical...
narrow-angle dark-field illumination
An imaging system designed to highlight small deviations in a planar reflective object such as a mirror. The system can be...
Fizeau fringes
Fizeau fringes are interference fringes observed in an interferometer, specifically in a Fizeau interferometer. The Fizeau...
stereolithography
A method of creating real three-dimensional models by using lasers driven by CAD software. In contrast to the normal...
spatial light interference microscopy
Spatial light interference microscopy (SLIM) is an optical microscopy technique that belongs to the category of quantitative...
Camera Link HS
Camera Link HS (high speed) is a standard developed for high-speed digital data transmission in machine vision and...
x-ray astronomy
The study of the celestial bodies, relative to x-ray emission. Satellites launched to study x-ray sources have revealed many...
dielectric cylindrical waveguide
A waveguide made up of a dielectric material, such as plastic or mica, in a cylindrical form, through which the waves travel.
scratch resistant coating
Thin layers intended to prevent damage to plastic optics.
electrophoretic display
An electrophoretic display, often referred to as an electronic paper display or e-paper display, is a type of electronic...
mercury arc
An electric arc that is formed in mercury vapor through which an electric current flows. The intensity of the illumination...
ballast resistance
In a laser, the series resistance necessary for a stable electrical discharge.
lens testing equipment
Lens testing equipment refers to a range of specialized tools and instruments used to evaluate the optical performance,...
blocking cement
An adhesive used to hold optical elements to blocking tools. It is usually a thermoplastic substance such as resin, beeswax,...
polysulfone resin
A thermoplastic, self-extinguishing polymer with excellent high-temperature, low-creep and arc resistance properties.
gastroscope
An optical instrument designed for the visual examination of the inside of the stomach.
button blocking
The production of a block by attaching the optical elements to a plate by means of individual buttons of pitch or other...
apparent contrast
The perceived brightness difference between light and dark areas on a target.
Weissenberg method
The Weissenberg method, named after the German physicist Karl Weissenberg, is a technique used in x-ray crystallography for...
dark-line spectrum
A spectrum having some lines that are darker than others or that contrast against a light, continuous-spectrum background.
veiling glare
Diffuse stray light at the image plane of an optical system that results in reduced contrast and resolution.
astronomical telescope
An astronomical telescope is a type of optical instrument designed to gather and magnify light from distant celestial...
master oscillation
 critical angle
The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at...
aversion response
Eye blink or head movement in response to bright light. Aversion responses such as blinking are sufficient protection from...
Liebmann effect
The visual perception of contrasting forms is more difficult if the forms have the same luminance but different...
contrast improvement
One area of image enhancement, accomplished by spatial filtering schemes, that usually involves attenuation of phase changes...
dilation
In image processing, a morphology operator in which a structuring element or probe of a particular shape is moved over the...
arc flash
An arc flash is a sudden release of electrical energy due to an electric arc — a continuous, high-current discharge of...
thermoplastic elastomer
A material used in the jacket of fiber optic cables.
Babinet compensator
A device containing two opposed quartz wedges of equal angle, one wedge being movable along its length by a micrometer...
metastable state
An excited energy state of an atom or atomic system that has a longer lifetime than the ordinary excited state and typically...
nadir
In a remote sensing system, nadir refers to the point on the ground located vertically below the center of the system. In...
photodiode detector
A photodiode detector is a semiconductor device that converts light into an electrical current. It operates based on the...
machine vision system
A machine vision system is an integrated combination of hardware and software components designed to capture, process, and...
unmanned aerial vehicle
An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot onboard. UAVs are remotely...
frames per second
The number of separate images exposed by a cine camera in a second or the number illuminated by a cine projector in a...
pyrolysis
A process that employs heat to remove polyimide plastic coatings from silica optical fibers and capillary tubing.
reflecting objective
An image-forming system that uses mirrors rather than lenses. Such objectives are frequently used for astronomical...
enclosed arc lamp
An arc lamp whose carbon electrodes are enclosed in a transparent chamber, resulting in an arc that is steadier, lasts...
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...
infrared astronomy
The study and the interpretation of the infrared emittances of celestial bodies and phenomena.
veiling brightness
A brightness, superimposed on the image of the retina, that decreases its contrast and that often results in decreased...
optical coherence tomography imaging system
Optical coherence tomography (OCT) is an imaging technique used in medical diagnostics and biomedical research to obtain...
polarizing filter
A filter that polarizes light passing through it. It is possible to fabricate sheets of plastic or gelatin that contain...
drift scan
An astronomical scanning technique for capturing images of stars without moving the sensor. To perform a drift scan, a CCD...
planar access coupler
Low-insertion-loss fiber coupler fabricated from a sheet of light-sensitive material laminated onto a fused quartz substrate...
high harmonic generation
High harmonic generation (HHG) refers to a nonlinear optical process in which intense laser light interacts with a gaseous...
double-raster format
A mode of laser printing in which each pixel is printed four times, providing sharper lines and a continuous tone from...
light diffusion
Light diffusion refers to the process by which light is scattered or spread out in various directions as it interacts with a...
antireflection coating
An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to...
attenuated total reflectance spectroscopy
Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples....
balloon-borne astronomical system
Any instrument or system carried by a balloon to the upper atmosphere to measure and record atmospheric information, such as...
optoacoustic
Optoacoustic, or photoacoustic, refers to a phenomenon and related techniques that involve the generation of acoustic waves...
Lyot filter
A type of filter consisting of a series of birefringent crystals and polarizers invented by French astronomer Bernard Lyot...
eye relief
Also termed eye distance. The distance between the vertex of the last optical surface of a visual optical system and the...
turbidity
Turbidity is a measure of the cloudiness or haziness of a fluid caused by the presence of suspended particles. These...
elastomer
Any material of a macromolecular nature that can stretch at room temperature to more than twice its length and return to...
surface acoustic wave
An acoustic wave that propagates along the surface of a solid and decays exponentially with substrate depth. Also called a...
diffuser
An optical diffuser is an optical component or material designed to scatter or diffuse light that passes through it. It is...
molded lens
A molded lens is an optical lens manufactured using a molding process, typically involving the shaping of a material, such...
transverse offset method
A technique used to measure the mode-field diameter of an optical fiber by scanning one fiber past another at a distance of...
case hardening
A surface heat-treating process that produces a highly stressed surface. In case-hardening of glass, a plate of glass is...
spectroscopy
Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves...
aspheric mirror
An aspheric mirror is an optical mirror surface that deviates from the shape of a perfect sphere, having a non-spherical...
split-crown triplet lens
A lens derived from the Cooke triplet anastigmat, but with one of the crown elements split in two, resulting in improved...
metabolite
A metabolite is any small molecule that is a product of metabolism, the chemical processes that occur within living...
Hartmann test
A test for spherical aberration, coma or astigmatism in which incident rays from a point source are isolated by small holes...
photon sieve
A photon sieve is an optical device used in the field of optics and imaging. It's designed to focus and shape light,...
x-ray phase contrast microscopy
Used for high-resolution surface study with subnanometer resolution. XRIM uses interfacial phase contrast with application...
organic light-emitting diode
An organic light-emitting diode (OLED) is a type of light-emitting diode (LED) technology that utilizes organic compounds to...
mirror lens
An image-forming system having curved mirrors in place of transparent glass components. Mirror lenses are commonly used for...
wave plate
An optical element having two principal axes, slow and fast, that resolve an incident polarized beam into two mutually...
gamma
A numerical value representing the degree of contrast in a television picture: the exponent of the power law used to...
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...
quantum sensing
Quantum sensing refers to a class of sensing technologies that leverage principles from quantum mechanics to enhance the...
angle-tracking system
A system in which a sequence of direct measurements of the target position is fed into a tracking filter that may produce...
phase-contrast microscope
A microscope that has an annular stop in the lower focal plane of the condenser, and a quarter-wave retarding and absorbing...
fata morgana
A type of mirage that creates a distorted vertical image of relatively flat objects so that they appear as mountains,...
hydrophobic
Hydrophobic is a term used to describe substances or materials that repel or do not readily interact with water. The word...
system
A combination of components arranged so as to perform at least one function.
frame rate
Frame rate refers to the frequency at which consecutive images, or frames, are displayed in a video sequence. It is...
rotating hologram
A disc composed of a series of holographic optical elements that diffract light at various angles. When spinning, a raster...
damped least squares
An organizational method used in optical design computer programs. The technique produces one number (merit function) to...
magnetic disc
A plastic disc coated with ferric oxide or other films on which data can be stored by selectively magnetizing areas of the...
diffraction scattering
Elastic scattering that occurs when inelastic processes eliminate particles from the beam.
sequential scanning
Raster scanning process like that of television: each line is scanned successively.
principle of least time
gray-scale modification
Image enhancement operations that involve altering gray-scale values. For instance, brightness sliding involves adding or...
excimer laser coronary angioplasty
Excimer laser coronary angioplasty (ELCA) refers to a medical procedure used in the treatment of coronary artery disease....
voltage contrast analysis
A nondestructive testing method for very large scale integration circuits, using a scanning electron microscope to monitor...
drift curve
A technique used in astronomy that requires a radio telescope to be directed at a point in the sky west of the object under...
astronomical unit
The unit generally used to express distances within the solar system, and sometimes to measure interstellar distances....
pushbroom scanning
Pushbroom scanning is a technique used in remote sensing and imaging systems, particularly in satellite and aerial sensors,...
opaque projector
An opaque projector is a device used for enlarging and projecting images from opaque objects such as printed pages,...
semilenticular screen
A projection screen having vertical ribs or flutes set into a plastic surface.
nonradiative transition
A nonradiative transition refers to a process in which an electron or an atom undergoes a change in its energy state without...
piezoelectric motion systems
Piezoelectric motion systems are mechanical systems that utilize piezoelectric materials to generate controlled motion or...

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