Photonics Dictionary

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...

A self-interference effect that generates random patterns; secondary speckle pattern (SSP) typically occurs in diffuse reflections of a laser on paper, white paint or rough surfaces. By tracking both...

In optical character recognition, the method of dividing a string of characters into separate, distinct characters.

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...

In optical emission spectroscopy, the reduction in radiant power in the central portion of spectral lines arising from the selective absorption by the cooler outer vapor of the source envelope of...

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...

Derived from "self-focusing,'' Nippon Sheet Glass Co. (NSG) of Japan's trade name for graded-index fiber rods with parabolic index profile, suitable for use as cylindrical microlenses.

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...

A polarizing beamsplitting prism similar in design to the Rochon prism. However, the Senarmont transmits the extraordinary ray without deviation and deviates the ordinary ray due to the orientation...

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...

1. A generic term for detector. 2. A complete optical/mechanical/electronic system that contains some form of radiation detector.

A device used in measuring attenuation in optical fiber. The loss caused by the bends in a short reference length of fiber approximates that of a much longer fiber under test.

Servo motion is the controlled motion of a mechanical system achieved through the use of a servo motor, which utilizes feedback mechanisms to ensure accurate positioning, speed, and acceleration....

A type of motor that acts as the control element in a servomechanism. It is powered by an amplifier circuit and drives the load with linear or rotary motion.

The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system. It is widely used in adaptive optics systems to correct distortions and...

Image distortion that occurs when the axes of the original image are not perpendicular in the resulting image, making the resulting image appear slanted. Shear can be caused by movement of the...

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...

An electronic flash tube in which the flash recurs at a frequency extending to many thousands per second. A stroboscopic light source is a short-flash light source.

Characterizes the significant solar radiation at the surface of the earth, so named because its spectral range extends only from 0.3 to 2.8 µm.

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

A device used to measure the opening time of a shutter. The most common devices depend on the charging or discharging of an electrical condenser, or on the production of a curve of open area against...

Systeme Internationale d'Unites, the international metric system of units.

Silicon carbide (SiC) light-emitting diodes (LEDs) are semiconductor devices that emit light when an electric current is applied to them. These LEDs are made using silicon carbide as the...

A material used as a protective layer on an aluminized or silvered mirror. It is evaporated on the mirror as a thin layer, and after exposure to the air the monoxide tends to become silicon dioxide...

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...

Technology that uses data from an array of sensors, one of which is commonly lidar, to solve the problem of creating a map of an unknown environment while simultaneously maintaining a location within...

A test chart whose luminance changes uniformly in one direction according to a sinusoidal rule. These charts carry groups of black lines on a white ground, the intensity profile across the lines...

A computer architecture used in parallel processing whereby the processing elements are directed by a single, central control unit; generally used for large numbers of relatively simple processing...

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...

Single-molecule Förster resonance energy transfer (smFRET) is a specialized technique in biophysics and molecular biology used to study the distances and dynamic interactions between two...

An advanced technique that allows the detection of one molecule within a crystal or a cell through optical excitation. Single-molecule spectroscopy (SMS) can image at subwavelength scales, down to a...