Photonics Dictionary

1. The decrease of the absorption (or gain) coefficient of a medium near some transition frequency when the power of the incident radiation near that frequency exceeds a certain value. As long as the...

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...

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.

A flat plate having its surface formed into a random pattern by abrasives. Radiation wavelengths that are longer than the scale of the pattern are specularly reflected; shorter wavelengths are...

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...

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

A Schottky diode is a type of semiconductor diode characterized by its low forward voltage drop and fast switching speed. It is formed by the junction of a metal and an n-type semiconductor, creating...

Schrödinger's cat is a thought experiment devised by the physicist Erwin Schrödinger in 1935 to illustrate the paradoxical nature of quantum mechanics, particularly the concept of...

A specific type of photographic plate designed with only a small amount of gelatin to function in the extreme ultraviolet and in positive-ray analysis.

A scientific CMOS (complementary metal-oxide-semiconductor) camera is a type of digital camera specifically designed for scientific imaging applications. It employs CMOS sensor technology, which...

Scientific complementary metal-oxide semiconductor (sCMOS) refers to a type of image sensor technology specifically designed for scientific and industrial imaging applications. Unlike traditional...

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 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...

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...

In multifocal spectacles, a term used to denote glass with a high refractive index that has been fused to the blank and ground to a curvature, resulting in added power.

In a bifocal spectacle lens, the vertical measurement of distance from the uppermost borderline of the bifocal segment to the lower lens edge.

In spectacle lenses, the lateral measurement of a multifocal segment at its maximum width.

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...

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...

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 term used to describe a spectacle lens or blank with one surface totally finished.

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.

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

A servo, short for servomechanism or servo motor, is a closed-loop control system that precisely controls the position, velocity, or acceleration of a mechanical component, typically in response to...

A type of color-generating cathode-ray tube that uses a shadow mask, a thin perforated electrode, located close to the display screen. Each hole in the mask coincides with a triad of three phosphor...

A three-dimensional grating designed with thin metal sheets to remain opaque to all but one specific and predetermined wave.

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...

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 convention that defines specific dimensions of an optical system, such as the image distance or radius of curvature of a lens or mirror, as negative or positive to facilitate calculations based on...

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 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...

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...

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...

Referred to as SWCNTs, these cylindrical nanostructures composed of a folded sheet of graphene can be used as near-infrared markers for small animal multiplex imaging. Emitting at different...

A singlet lens is an optical lens made from a single piece of material, typically glass or plastic, with one or both surfaces being spherical or aspherical. It is the most basic type of lens used in...

A singulated die refers to an individual semiconductor chip that has been separated or singulated from a larger wafer. This term is commonly used in the semiconductor manufacturing industry. ...