Photonics Dictionary: S

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...

A disc, having opaque and transparent sectors or sectors with unlike reflectances, that is rotated at a specific rate to form a continuous response to the average energy transmitted or reflected by...

1. In glass, a solid inclusion having a small diameter. 2. A particular, single crystal that, after undergoing the Czochralski method, evolves into large single crystals.

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...

The reflection in different amounts as a function of wavelength, as a result of absorption and scattering, leading to color effects if occurring in the visible wavelength region.

Transmission in different amounts as a function of wavelength, as a result of absorption and scattering, leading to color effects if occurring in the visible wavelength region.

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...

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

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...

In a radiation detector, the ratio of the output to the input signal.

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...

Primarily the measurement of photographic sensitivity of certain materials such as photographic film. It refers to the measurement of the response of photographic materials, after exposure, to forms...

Three filters used in making a color print of a color negative, red, green and blue-violet, respectively. Each filter transmits about one-third of the visible spectrum onto the print.

A type of motion-picture camera in which single frames are photographed either automatically at a predetermined rate (as slow as one frame per minute or hour), or whenever the operator presses a key....

With respect to television, the transmission of the signals that originate from variously colored parts of an image in a particular sequential order.

Raster scanning process like that of television: each line is scanned successively.

A variation of tomography, which is a means of visualizing any one of a large set of parallel planes in the patient. A series of x-ray pictures taken from different angles results in developed...

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.

A handheld navigational instrument used to measure the elevation angle of celestial bodies such as the sun. An image of the sun is viewed through a small telescope via two plane mirrors so that any...

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...

A term used to denote a concave surface having too long a radius of curvature. That is, its negative power is too small or low.

A term used to describe a convex surface having too short a radius of curvature. To correct this condition, material is cut from the outer portion of the polishing tool.

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 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...

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 solid-state device, composed of silicon, that is used to convert radiation into electrical energy.

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...

The ability of an electrical current to destroy superconductivity by means of the magnetic field generated by the current. The temperature of the material is not raised, and the effect is identical...

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...

A short focal length (less than five inches) positive lens used to produce a magnified image of the object being viewed. While a single element will function, an achromat or multielement assembly...

A passive infrared system that uses two line-of-sight telescopes to generate both narrow and wide field-of-view images of the same target area, which can be presented on a single split screen or on...

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...

In a dual-ring local area network, a node that is connected only to the primary, active ring and not to the secondary ring that provides a backup in case of cable or system failure.

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...