Photonics Dictionary

Förster resonance energy transfer (FRET) is a mechanism describing the transfer of energy between two closely spaced fluorescent molecules. This phenomenon is named after the German scientist...

Voltage that produces current flow in the direction of lesser resistance to the steady-state direct current, i.e., from the anode to the cathode.

A polarizing prism formed from calcite that is like the Nicol prism but has the two parts divided by a thin air-film and cut to such angles that the extraordinary beam will be transmitted and the...

An instrument using a Michelson interferometer, a beamsplitter, two plane mirrors and a detector to give Fourier analysis of the detector signal to provide the desired spectrum.

A laser skin-resurfacing method that creates microscopic thermal wounds referred to as microscopic treatment zones (MTZs), which are surrounded by uninjured tissue. The MTZs are usually arranged in a...

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 the connected multiple images on motion-picture film. 3. The size of the...

A frame grabber is a hardware device or interface card that connects to a computer or imaging system and is designed to capture and digitize frames of video or images from a video source such as a...

Frame rate refers to the frequency at which consecutive images, or frames, are displayed in a video sequence. It is typically measured in frames per second (fps) and determines the smoothness and...

A device that permits the adjustment of facsimile transmitters and recorders so that their scanning lines stop and start at the same place in relation to the subject copy.

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

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.

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 frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with great accuracy. The term "frequency comb" is often associated with the Nobel...

The frequency domain is a concept used in signal processing and analysis to represent signals and data in terms of their frequency components. In contrast to the time domain, where signals are...

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

Fresnel reflection refers to the reflection of light at the interface between two different media with different refractive indices. This phenomenon was named after the French engineer and physicist...

A calculated function that can be achieved experimentally with interferometric analysis of complex atmospheric altitude; expressed as a relation to the turbulence integrated over the entire...

A piece of uniform birefringent material placed at a 45° angle to the plane of polarization in a polarizing microscope to indicate changes in color caused by interference when a birefringent...

Molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube. Also called buckyballs. Cylindrical fullerenes are called carbon nanotubes or buckytubes.

A computer hardware unit that generates required functional information on the screen by controlling CRT beam movements or intensity.

Functional materials refer to materials that possess specific properties or functionalities that make them suitable for particular applications or purposes. These materials are designed and...

Fused quartz and silica are closely related materials, both composed primarily of silicon dioxide (SiO2), but they are produced through different manufacturing processes and have distinct properties...

Fusion ignition refers to the point in a controlled nuclear fusion reaction where the energy released by the fusion reactions becomes self-sustaining, leading to a continuous release of energy...

A GaAlAs laser is a type of semiconductor laser diode that emits light in the near-infrared region of the electromagnetic spectrum. It is composed of layers of gallium, aluminum, and arsenic, hence...

Also known as amplification. 1. The increase in a signal that is transmitted from one point to another through an amplifier. A material that exhibits gain rather than absorption, at certain...

Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium. This method is distinct from Q-switching and mode-locking, two other common...

A laser system consisting of a planar PN junction within a single crystal of gallium arsenide. The pair of parallel, semireflective end faces produces a Fabry-Perot resonant cavity, whereas the other...

Gallium arsenide phosphide (GaAsP) is a semiconductor alloy composed of gallium (Ga), arsenic (As), and phosphorus (P). It is commonly used in the fabrication of optoelectronic devices, particularly...

A galvanometer is an instrument used for detecting and measuring small electric currents. It typically consists of a coil of wire suspended in a magnetic field, with a pointer attached to the coil....

A galvanometric scanner, also known as a galvanometer scanner or galvo scanner, is a type of optical scanning device used to rapidly and precisely direct a laser beam or other light source to...

Modification of a system to provide for a linear transfer characteristic from an input to an output device. A circuit for this purpose is built into a television camera to compensate for display tube...

The spontaneous emittance of electromagnetic radiation by the nucleus of certain radioactive elements during their quantum transition between two energy levels. The radiation emitted has a wavelength...

GaN (gallium nitride) distributed feedback (DFB) lasers refer to a specific type of semiconductor laser based on Gallium Nitride materials and designed with a distributed feedback structure. These...

Gallium nitride-based light-emitting diodes (GaN-based LEDs) are semiconductor devices that emit light when an electric current passes through them. These LEDs are constructed using gallium nitride...

One of the first lasers to find practical application. Generally, the pumping mechanism is an electric discharge, although some high-power forms employ chemical reaction or gas compression and...

A gas laser wherein the gas mixture is not exhausted into the atmosphere but is continually recycled. It is excited in the active region, cooled and re-excited. The GTL requires no constant gas...

A beam of light whose electrical field amplitude distribution is Gaussian. When such a beam is circular in cross section, the amplitude is E(r) = E(0) exp [-(r/w)2], where r is the distance from beam...

1. That branch of optics that illustrates the theory in which q is substituted for sin q in Snell's law. Effective results are achieved if the aperture and field angle are made very small. The...

The masking of all openings of an optical transform -- except the hole at the symmetrical center -- with a thin wire gauze to attain a more precise image.

A photometer used to measure sky brightness and polarization associated with zodiacal light, background starlight, F-region airglow and spacecraft corona.

A rapid roughing process for the quick removal of glass, the first step in manufacture of a curved lens surface. It is accomplished with coarse emery or a diamond-impregnated tool.

The curved mark formed when, in the process of generating, a loose or coarse diamond particle from the generating tool scores the work so deeply that subsequent fine grinding or polishing cannot...