Photonics Dictionary

Scanning characterized by the generation of a plane or right circular cone with a vertex angle of about 180° by the direction of maximum radiation.

The halo phenomenon of a brightly colored arc having the colors of the rainbow and lying parallel to the horizon.

In optics, degreasers or ultrasonic arrangements used for removing pitch, cement or polishing material from lenses during manufacture. It also may refer to manual cleaning devices used immediately...

The application of photography, with the exception of radiography, to obtain pictures of parts or the whole of a patient to make a diagnosis.

A fiber optic communications system that works on the principles of homodyning or heterodyning. The transmitting laser produces an optical wave that is modulated in amplitude, phase or frequency by...

The use of phase conjugation or other methods to increase the power density of a laser beam under adverse atmospheric conditions.

The broadening of spectral lines due to the collision of radiating particles with one another and the resulting interruption of the radiative process.

An instrument providing a continuous measure of color.

A laser warning and countermeasure system containing a sensor that indicates the direction of a laser beam, and analytical instruments to determine pulse code, repetition frequency and wavelength.

The maximum rate at which temporally disjunct optical signals can be produced or detected.

The use of a computer to generate a series of interrelated images so that the images give the illusion of movement in space and time.

A microscope design that involves apertures inserted in conjugate plane positions inside the microscope, with one aperture in front of the illumination source and the other at the focal position in...

The dispersion of a light ray striking the surface of a biaxial crystal, in which the resulting rays are reflected in a conical manner.

A parabolic, elliptical, hyperbolic or circular section created when a solid cone is intersected by a plane.

A lens with a surface that is a cone instead of the usual sphere.

A device used to determine the location and attitude with respect to the Earth of orbiting spacecraft by detecting the difference in thermal radiance between the Earth's horizon and space.

A converging lens with one convex and one concave surface.

A cryogenically cooled long-wave infrared (LWIR) camera is a specialized thermal imaging device designed to detect infrared radiation in the long-wave infrared spectrum, typically ranging from 8 to...

The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).

A technique for measuring fiber attenuation or distortion by performing two transmission measurements. One is at the output end of the full length of the fiber. The other is within 1 to 3 m of the...

Popular process for silicon and polycrystalline production that consists of an alteration of the original state of a substance; thus, single-crystal materials can be used to form a polycrystal.

The formation of a dark-colored film on a metal surface by chemical activity.

A device used in ultrasonic imaging to measure the velocity and attenuation of compressional waves in a transparent liquid by virtue of acoustic waves set up in the liquid. The wavefronts serve as a...

An approach to optical character recognition based on matching the input character against a set of stored prototypes.

Deep learning is a subset of machine learning that involves the use of artificial neural networks to model and solve complex problems. The term "deep" in deep learning refers to the use of deep...

The clarity of an optically reproduced image. Definition is produced by the combination of resolution and acutance.

A chart, either printed on paper or prepared photographically on glass plates or film, that consists of 3-bar resolution test objects, sine-wave test objects for modulation transfer function...

Diamond turning, also known as diamond machining or diamond cutting, is a precision machining process used to produce high-quality optical surfaces and components with extremely tight tolerances. It...

Dichalcogenides are a class of compounds composed of two atoms of a chalcogen element bonded to a single atom of a metal or metalloid element. Chalcogens are the elements in group 16 of the periodic...

The formation of a fan of light or energy rays in a beam as the beam passes through an extremely narrow aperture.

Digital Imaging and Communications in Medicine (DICOM) is an international standard for medical imaging created by both the National Electrical Manufacturers Association (NEMA) and the American...

Also called DLIP, a high-speed, high-resolution processing technique that uses high-power, pulsed laser systems to directly ablate micro- and nanoperiodic structures with different features on large...

A scanning technique in which the object is illuminated the entire time, and in which picture elements of the object are viewed singly by the television camera.

A lens with one surface convex and the other concave, the latter having the greater curvature. It also is known as a diverging meniscus lens.

The spreading of potentially equal radiation frequencies that results in broadening of the spectral line. This effect is brought about when radiating atoms, molecules or nuclei have different...

See periscopic lens; rapid rectilinear lens.

The deflection of a beam of electrons, at regular intervals, across a cathode-ray tube screen, according to a definite pattern.

The method by which photographic film is scanned by an electron beam. One technique uses the uniform light of a television screen, focused by a lens onto the processed film, as a means of creating a...

The point at which short-wavelength transmission is cut off.

The bands of spectral lines representing the electronic transition in a molecule.

A small xenon-filled tube with metal electrodes fused into the ends. The gas flashes brilliantly when a condenser is discharged through the tube. The duration of the flash is primarily dependent upon...

A method that uses electronic means to move the scanning spot along the scanning line.

A mechanical shutter that has had its timing escapement replaced with an electronic timing circuit. This circuit allows a wider range of exposure times, can be more accurate, and, placed in a circuit...

A term applied to the recording of video images by means of magnetic tape or disc, so that the image's record can be played back in a video format at a later time.

A small television monitor that replaces the reflex viewfinder in a television camera.

In target tracking, a technique for speeding up the image processing by removing bunches of pixels that are outside the area of interest.

The use of an electric field or signal to couple a lightwave from one dielectric waveguide into another dielectric waveguide.

That branch of science involved in the study and utilization of the motion, emissions and behaviors of currents of electrical energy flowing through gases, vacuums, semiconductors and conductors, not...

Magnification that is above the level of maximum useful magnification and does not contribute useful resolving power. In a visual telescope, empty magnification is any in excess of 20 D, where D =...