Photonics Dictionary

A phosphor that has the ability to convert into light emission a portion of energy lost by ionization when a charged particle passes through the material.

An instrument that uses an image intensifier to aid in the viewing of subjects in low-light-level environments.

A nonlinear label-free imaging technique commonly used during surgical procedures for the visualization of collagen fibers and muscle tissue (myosin) with submillimeter resolution. During the...

Second-harmonic generation (SHG) is a nonlinear optical process that occurs when two photons with the same frequency combine within a nonlinear material, resulting in the generation of a new photon...

Second-order nonlinear optical properties refer to a class of phenomena exhibited by certain materials in response to intense light, typically in the realm of optics and photonics. Nonlinear optical...

An aberration that remains after primary color is corrected. Primary color causes the back focus of a lens to vary with wavelength; for example, blue light comes to focus closer to the lens than...

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and physicist Ludwig von Seidel. These aberrations describe deviations from...

Selective laser melting (SLM) is an additive manufacturing (AM) or 3D printing technology that belongs to the powder bed fusion category. SLM is primarily used for metal additive manufacturing, where...

An optically bistable device used for photonic switching, constructed of a multiple quantum well biased by an external voltage, which creates an external field that shifts the wavelength of the onset...

Self-phase modulation (SPM) is a nonlinear optical phenomenon that occurs when an intense laser beam passes through a medium, causing a change in the phase of the light due to its interaction with...

An equation that uses the wavelength of light passing through a medium, along with a set of coefficients, to calculate the medium's index of refraction. The coefficients, called Sellmeier...

A semiconductor is a type of material that has electrical conductivity between that of a conductor and an insulator. In other words, semiconductors have properties that are intermediate between...

An instrument for determining the sensitivity of a photographic film to light. The film is given either a stepped exposure or a continuously varied exposure; after processing, the density is measured...

An avalanche photodiode in which the light-absorbing area is a low-bandgap material and the PN junction is placed in an area of high-bandgap material, reducing dark current and increasing gain.

A sheet of plastic material containing microscopic crystals of herapathite or some other similar substance that transmits light polarized in one direction, but absorbs light polarized in a...

Short wavelength infrared (SWIR) refers to the portion of the infrared spectrum that encompasses wavelengths roughly between 1,000 and 3,000 nanometers (nm). In the electromagnetic spectrum, infrared...

A compact high-pressure light source in which an electrical discharge between electrodes spaced no more than 12 mm apart occurs in a xenon or other gas medium, providing a visible light resembling a...

A mechanical or electronic device used to control the amount of time that a light-sensitive material is exposed to radiation.

A type of fiber optic cable that emits light from its sides along its length.

A silicon photodiode is a semiconductor device that converts light into an electrical current. It is a type of photodetector specifically designed for detecting and measuring light intensity. Silicon...

An emulsion in which grains of the photosensitive material silver halide are deposited. Each grain, when exposed to light, either develops or fails to develop as a unit, leaving a dark or clear...

Bar pattern represented as a sine curve in which the light distribution varies in one direction.

Single molecule localization microscopy (SMLM) is a group of super-resolution microscopy techniques that surpass the diffraction limit of traditional optical microscopes, allowing for the...

A single-photon avalanche diode (SPAD) is a specialized type of photodetector designed to detect extremely weak optical signals, down to the level of single photons. SPADs are widely used in...

A technique for observing the decay of light emissions from sources following their pulsed excitations, based on recording the arrival time of the first photoelectron after excitation. After many...

Sisyphus cooling is a technique used in atomic physics to achieve ultracold temperatures of atoms or molecules by exploiting the periodic motion of particles in optical traps or lattices. The name...

The angle at which photoelectric sensors are aligned to prevent light from being reflected back to the sensor from the object during retroreflective sensing; also, the angle a measured part is...

An aperture, usually rectangular in shape, with a large length-to-width ratio, and a fixed or adjustable shape through which radiation enters or leaves an instrument. The aperture is generally small...

A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the substance often forms drops that display a series of fine lines. X-ray...

A transmission interference microscope that produces interference patterns of a sample by using birefringent plates that split a polarized beam of light into ordinary and extraordinary rays, then...

A lens that exhibits spherical aberration when used at large aperture settings, and that forms an image with a slightly blurred outline.

A device for converting sunlight into electrical energy, consisting of a sandwich of P-type and N-type semiconducting wafers. A photon with sufficient energy striking the cell can dislodge an...

The simulation of solar radiation in the infrared and ultraviolet spectrum for the analysis of extraterrestrial sunlight and its effects on spacecraft, materials and components.

A solar simulator is a device used to replicate the spectrum and intensity of sunlight in a controlled environment for testing and research purposes. Solar simulators are employed in various...

Optical elements arranged with no spaces between, so that the light travels only through glass, not air.

An imaging system that uses a mosaic of tiny light-sensitive semiconductors (phototransistors) to produce individual outputs that are then converted into a coherent video signal.

A solid-state laser is a type of laser that uses a solid gain medium (as opposed to a liquid or gas) to produce coherent light. The term "solid-state" refers to the fact that the active medium, where...

Any isolated wave that propagates without dispersion of energy. Specifically to photonics, an ultrashort pulse of laser light that propagates through a waveguide without characteristic chromatic...

The process whereby sound waves are employed to form a three-dimensional image of an object. The process involves generally: the recording of the diffraction pattern of an object exposed to sound...

The relationship between different wavelengths of light generated by a source, which may affect the spectral distribution of the light as it travels great distances in space; put forth by physicist...