Photonics Dictionary

In ophthalmic practice, an instrument that determines the boundaries of the field of view. It is composed of a 2-m square of black velvet with a white spot center at which the patient, 1 m away,...

A type of scratch.

A photometer screen that contains a diaphragm of paper or parchment with a translucent central spot of oil or paraffin.

The deformation of a material at high levels of stress, often associated with elevated temperatures.

A structural method of optical character recognition, used where the input media are variable, as in hand-written or multifont documents. A series of questions (such as "Does the character contain a...

A quantitative measurement of the coherence of a light source; equal to the visibility (V) of the fringes of a two-beam interference test: where Imax equals the intensity at a maximum of the...

The number of unique ways in which a part can move in an alignment system. In static alignment, there are six: one in the direction of and one in rotation about each of the X, Y and Z axes. In...

In printing, a translucent screen used with lenses to provide an even distribution of diffused light.

In a camera, the focusing of an image on the screen located at the camera's film plane. Once the image is in complete focus, the recording medium is inserted in place of the screen.

A CRT screen on which two phosphors differing in color and persistence are deposited.

A fluorescent screen refers to a phosphorescent or fluorescent-coated surface that emits visible light when exposed to other forms of electromagnetic radiation, such as x-rays or ultraviolet light....

Short-lived molecular or atomic particles, with an unpaired electron, that play an important part in many photochemical reactions.

The process whereby a rotating wheel carries grains of an abrasive, suspended in a vehicle, across the surface of the optical glass to be ground. The workpieces are forced downward by pneumatic...

The phenomenon whereby an electron within a band absorbs radiation by transferring from a low-energy level to an empty high-energy level.

Photoconductivity that may be extended as far as the microwave region because of the absorption of photons by electrons.

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

A type of internal photonic connection in an integrated circuit in which a holographic grating is used to focus light at points on a silicon chip, maximizing the speed of signal propagation.

Free-space optics (FSO), also known as optical wireless communication or optical wireless networking, refers to the transmission of data using modulated beams of light through free space (air or a...

The frequency space between consecutive transmission peaks in the transmission spectrum of a Fabry-Perot interferometer or etalon. The free-spectral range is inversely proportional to the distance...

Freeform mirrors refer to reflective optical components that deviate from traditional symmetric or rotationally symmetric shapes, such as spheres or paraboloids. Unlike conventional mirrors, which...

Freeform optics refers to the design and fabrication of optical surfaces that do not follow traditional symmetric shapes, such as spheres or aspheres. Unlike standard optical components with...

A porous ceramic substance that is ground to a given optical form and on which a polished plate of glass is sagged by heat application. It is capable of transmitting in a partial vacuum. The glass...

Familiar term for CD/I disc. The CD/I standard also is known as the green standard.

A form of a stereoscopic microscope having paired objectives, prisms and eyepieces, and invented by H. Greenough.

A plate containing a uniform pattern of transparent holes in an opaque background, the clear area being nearly equal to the opaque area. Used in the printing process.

Also known as HCS, an analytical method designed to collect statistically relevant amounts of quantitative data on many parallel cell populations or processes within cells through the combination of...

A screen with a reflected or transmitted light beam that is confined to a much smaller bundle than was received by the screen, thereby resulting in a higher luminance.

A thermal infrared imaging procedure developed for quality control of printed circuit boards. The thermogram of each board under test is compared with a standard thermal profile and then with a...

Label-free refers to a technique or method that does not require the use of additional labels, tags, or markers to detect or identify specific components or entities. In various scientific and...

A rear or front projection screen composed of minute optical surfaces that introduce a spread to the light beam that conforms approximately to the light distribution requirements of the application.

A collector for photovoltaic power generation that consists of a thin plate that strongly absorbs sunlight striking its faces and luminesces efficiently. A large fraction of the luminescence is...

An approximated measure of the smallest change in color temperature detectable by the human eye, defined as the reciprocal of the color temperature times 106. Also called mired or reciprocal...

A lenticular screen having the lenticules tipped about 20° to compensate for off-normal projection.

A phase screen, in the context of optics and wave optics, refers to a surface or medium that introduces a phase delay to an incident wavefront passing through it. This concept is often used in the...

A solid-state panel of the photoconductor-electroluminescent type. The photoconductive layer, sensitive to x-rays, is coated by the electroluminescent, which gives the visible image. When the former...

The transparent component of an optical reader that transmits the image rays of the characters to be read.

RGB stands for red, green, blue, which are the primary colors of light used in additive color mixing. The RGB color model is widely used in various electronic displays, such as computer monitors,...

The large, usually flat surface onto which an image is projected for viewing. May be reflecting or transmitting (rear projection).

A projection screen having vertical ribs or flutes set into a plastic surface.

Integral densities that are measured relative to arbitrarily selected red, green and blue filters.

Referring to compound semiconductor materials combining one element that has three valence electrons with one or more that have five. Examples include gallium arsenide and indium antimonide. (III-V).

A laser having a material, such as ruby, that has an energy state structure of three levels: the ground state (1) wherein excitation applied to the material raises ions in the material into the...

Three-photon microscopy is an advanced imaging technique that belongs to the family of multi-photon microscopy methods. It is used in biological and medical research to capture high-resolution images...

A screen composed of a sheet of diffusing plastic material that reveals excellent image detail for close viewing. It is efficient for use with microfilm readers.

A testing device that provides a contour map of the emergent wavefront for the observer in terms of the given wavelength of the light.

A 3D profile sensor, also known as a 3D profiling sensor or 3D depth sensor, is a technology that is used to capture and measure the three-dimensional shape or profile of an object or a scene. These...

The limited light-gathering area of an optical system. The area is normally restricted to an edge or outer surface of an individual component. Also known as free aperture or objective aperture. The...