Photonics Dictionary

The negative distortion that causes a square grid pattern to be imaged as barrel-shaped.

That point in a Gaussian beam where the wavefront has a curvature of zero and the beam diameter is a minimum.

A birefringent crystal having two axes along which there is an absence of double refraction. Mica, sulphur and turquoise are biaxial crystals.

Unified notation for specification of reflectance in terms of both incident- and reflected-beam geometry; i.e., the ratio of reflected radiance in direction toward the viewer to the irradiance in...

The glossy appearance of an object viewed, because of the binocular combination of two very unlike colors.

The action of a biological system responding to a single or multiple coherent particles of light produced from a laser source. Examples of laser biostimulation include: retinal interaction of light...

A matrix-controlled display that has information storage at the display surface, and requires that an element be addressed only once to assure that it is on or off.

Characteristic of a reflector that reflects light along a different line or lines than that of the incident ray.

A ground-based navigation beacon that emits pulsed signals which are picked up by aircraft making an instrument (blind) approach in landing. The signal is transmitted to the aircraft's L-scan...

An extended bubble or seed on glass, elliptically shaped and more than one-quarter inch (6.3 mm) in length.

An edging stone having a relatively coarse abrasive.

A constant equal to the universal gas constant divided by the Avogadro number. It is approximately equal to 1.38 x 10-23 J/K and is commonly expressed by the symbol k.

A Bose-Einstein condensate (BEC) is a state of matter that forms at temperatures close to absolute zero. It is named after Satyendra Nath Bose and Albert Einstein, who independently predicted the...

A technique in which a beam of x-rays is directed against a crystal, the atoms of which, because of their lattice arrangement, reflect the ray in the same way as a series of plane surfaces. If the...

Electromagnetic radiation that is emitted by an electron as it is accelerated or decelerated while moving through the electric field of an ion.

A parallel plate of glass in such a position that the refracted and reflected rays of incident parallel light are mutually perpendicular. In this situation the reflected light is plane polarized, and...

For light incident on a plane boundary between two regions having different refractive indices, the angle of incidence at which the reflectance is zero for light that has its electrical field vector...

The fringes used in the Jamin interferometer and produced by light that has been internally and externally reflected by two plane-parallel plates, inclined toward each other at a small angle.

A sound wave that travels through a piezoelectric material.

A high-frequency pulse-rate laser with an output limited by the heat capacity of the laser medium. Instead of having continuous cooling, the laser operates until the medium reaches a maximum...

The measure used in vacuum technology to quantify the total pressure capacity of the ferrofluidic seal before it fails.

White, tetragonal crystals used in the production of luminous coatings.

A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola. The image formed is free of spherical aberration and color and is located...

A caustic formed by reflection.

A system that uses both reflection and refraction to achieve its focal power. While the relative powers of the lenses and mirrors vary from system to system, the use of the reflective surfaces to...

The darkening of the laser facet of a semiconductor laser diode. It can be prevented by placing the component in a hermetically sealed enclosure.

Also known as cathode rays. Formerly, this term described a stream of electrons emitted from the cathode of a gas-discharge tube during its bombardment by positive ions. It also describes any stream...

An optical system in which the only image-forming elements are curved-surface mirrors; e.g., a Cassegrain lens system.

A surface that envelops a bundle of rays or bundle of normals to the wave surface. It may be observed as a hollow, luminous cusp in a turbid medium.

In an interferogram, an intense portion of the recording that corresponds in size to the amount of infrared radiation incident on the detector.

A lens system in which the centers of curvature of all surfaces fall on a common axis.

In a reflecting telescope, the obstruction of the primary mirror by a secondary mirror which blocks a small amount of the light reflected by the primary mirror and introduces additional diffraction.

The creation of a diode laser structure by liquid-phase epitaxy over a grooved substrate.

A photoelectrically controlled, alphanumeric reading device that converts characters to audible or sorting signals which can be fed to a computer, electric typewriter, tapepunch or other machine.

The angle at which a given mode propagates down an optical fiber.

A graph used in photography to portray the increase of a film's density as its time of exposure increases.

The state of a liquid crystal in which the molecules are arranged in layers with their long axes in the plane of each layer. The alignment in each layer is parallel and the alignment in adjacent...

The monochromatic transparency effect produced by the immersion of a finely powdered substance (e.g., glass or quartz) into a liquid with a similar refractive index.

A transparent powdered solid immersed in a liquid or plastic of similar refractive index but widely different dispersion; used to isolate narrow spectral regions.

Methodology for specifying color based on the CIE sources, observers, and coordinate system.

Best point of focus for an image in a beam of light at the smallest cross section of the beam.

A mechanism or device, especially a coating with a refractive index equal to or slightly greater than that of an optical fiber's cladding, that removes modes propagating through the cladding by...

In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.

A television system that does not broadcast television signals but transmits them over a closed circuit.

This type of miniaturized system, referred to as CMOS qPCR, combines microfluidic technology with an ultralow-light CMOS bio-optical sensor with LEDs as the optical excitation source to achieve...