Photonics Dictionary: S

A device that acquires a signal and then stores it for a specified period of time before processing, and used, for example, to reduce noise as in correlated double sampling.

Sapphire crystal refers to a transparent, single-crystal form of aluminum oxide (Al2O3) known as corundum. It is one of the hardest known materials, second only to diamond on the Mohs scale of...

Sapphire optical fiber is a type of optical fiber made from single-crystal sapphire, which is a form of aluminum oxide (Al2O3) that is highly transparent in the infrared region of the electromagnetic...

A sapphire window refers to a transparent optical component made from sapphire crystal. Sapphire is a single-crystal form of aluminum oxide (Al2O3) that is highly prized for its exceptional optical...

Sapphire refers to a crystalline form of aluminum oxide (Al2O3) that is used in various optical and photonic applications due to its exceptional optical, mechanical, and thermal properties. Sapphire...

A contour mapping technique that uses electronic scanning and sampling techniques instead of a reference grating (see moire topography; projection moire topography) to obtain moire fringes, producing...

A form of infrared CCD that utilizes internal photoemission as a photodetection mechanism.

Irradiance per unit wavelength interval at a given wavelength, expressed in watts per unit area per unit wavelength interval.

A defect in the cleaved end face of an optical fiber in which the surface changes abruptly.

A scanning process in which the greatest amount of radiation determines part of a spiral motion rotating in one direction.

A cooling system used to attain and maintain desired low temperatures in infrared systems. The Stirling type is a mechanical refrigeration system capable of temperatures from 10 to 77 K.

Employ a Stirling engine for cryogenic cooling.

An engine in which work is performed by the expansion of a gas at high temperature; heat for the expansion is supplied through the wall of the piston cylinder.

Birefringence of materials that is induced or altered by stress fields.

A method of polishing an aspheric surface by mechanically distorting the optic while polishing the surface to a perfect sphere. When the stress is released, the substrate assumes the desired aspheric...

An image of an object that appears above the object's true position as the result of abnormal refraction of the image rays by the atmosphere.

A liquid crystal display using the material in its supertwisted nematic phase; the birefringence of the liquid crystal results in a characteristic yellow or blue color, unless corrected.

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 special-purpose polarimeter having a scale calibrated directly in the concentration of sugar in the test solution.

The shape of the edge of a concave surface when the depth of the bevel plane to the vertex of the surface is controlled to a required distance.

Sagnac interferometry is a technique used to measure rotation or angular velocity based on the principle of interference. It relies on the Sagnac effect, named after the French physicist Georges...

Formula that describes the thermal equilibrium of gas electrons and ions as a direct function of variations in temperature.

The simultaneous exposure of two holographic plates with emulsions facing the object. After deformation, a second pair of plates is exposed to the deformed object. The back plate of the initial pair...

A direct-readout television pickup tube.

A double-plate device used to transmit polarized light and form interference fringes of the light, thus indicating its presence. It consists of two calcite plates of equal thickness, cut parallel to...

Scalar diffraction theory is a simplified approach used to describe the propagation of electromagnetic waves, particularly light, as they encounter obstacles or apertures. It is termed "scalar"...

In coherence theory, an optical law put forth by physicist Emil Wolf that explains the behavior of light as it travels away from its source over large distances in space. Light spectra are assumed to...

1. A device used to trace out an object and build up an image. One of the most common of these types is video scanning. The scanning takes place inside the television tube as electrons, guided by...

A scanning electron microscope (SEM) is a powerful imaging instrument used in scientific research, materials characterization, and various industrial applications. Unlike traditional optical...

Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution, three-dimensional images of the surfaces of solid specimens. SEM achieves this by...

A specific type of filter designed to reduce the amount of light scattered by reflections from the edges of optical components or mounts, or from irregularities on the optical surfaces.

The photomicrographic recording of Schlieren effects, irregular refractions of light from optic surfaces or areas of thin, transparent specimens, generally using a reticle with parallel transparent...

A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the mirror. The purpose of the plate is to correct the spherical aberration of the...

Oscilloscope electronic circuit that produces an output pulse whose pulse width is determined by the time that the output voltage exceeds a specified level.

1. The variation in intensity of a light beam as it travels through the atmosphere. 2. In radiation physics, a light flash formed by an ionizing event in a phosphor; a flash formed when rapidly...

An instrument designed to measure radiation indirectly through the use of several phosphors and a photomultiplier tube. The absorption of radiation by any phosphors results in light flashes that may...

A scintillation crystal, also known simply as a scintillator, is a material that emits light when it interacts with ionizing radiation such as gamma rays, x-rays, or charged particles. The emitted...

A scintillation detector is a radiation detection device that utilizes scintillation crystals to detect and measure ionizing radiation, such as gamma rays, x-rays, or charged particles. It consists...

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

A defect on a polished optical surface whose length is many times its width. Block reek is a chainlike scratch formed in polishing. A runner cut is a curved scratch caused by grinding. A sleek is a...

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...