Photonics Dictionary: S

Frequently used in astronomical measurement, it is based on the diurnal rotation of a star relative to the fixed stellar system.

In Stimulated Brillouin Scattering (SBS), an incident photon (usually laser light) interacts with acoustic phonons in a medium. The energy and momentum of the incident photon are transferred to the...

Radiation similar in origin to spontaneous emission but determined by the presence of other radiation having the same frequency. Because the phase and amplitude of the stimulated wave depend on the...

Light from a pulsed laser focused into nonsaturable absorbing fluid that generates a strongly backscattered light beam with a frequency higher than that of the incident light.

Interval between cutting off a photoconductor's signal and the fall of current output to 90 percent.

STED microscopy, or stimulated emission depletion microscopy, is a superresolution imaging technique in fluorescence microscopy that surpasses the diffraction limit, enabling the visualization of...

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.

A saturable absorber is a type of optical device that exhibits variable absorption properties depending on the intensity of incident light. In essence, it becomes less absorbent as the light...

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"...

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 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...

Vision by means of retinal rods; vision of the dark-adapted eye. In scotopic vision, the level of luminance is so low that the retinal cones are not stimulated, and there is no color vision.

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...

The indistinct rainbow that may sometimes be observed outside the distinct primary bow and that has its colors in opposite order. The red colors of both bows are toward each other.

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...

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....

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 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...

Also referred to as the width of the dark pulse. This is the time interval between the instant the particle approaches the beam and the instant the particle leaves the beam.

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...

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...

A crystal, glass, or quartz slicing and cutting machine is a specialized piece of equipment used in the manufacturing process to precisely cut and slice materials such as crystals, glass, and quartz...

The letter form used on visual performance test charts. The overall letter height is equal to five times the thickness of individual strokes. Normal 20/20 vision is represented by the ability to...

Solar radiation intensity existing in free space at the mean solar distance of the Earth. Commonly expressed in g cal cm-2min-1, the constant is equal to the amount of incident radiation -- in unit...

The process of transferring collected energy from solar radiation into a heat-absorbing medium (e.g., an insulated tank of water) for use at a later time.

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...

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...

A spatial light modulator (SLM) is an optical device that modulates or manipulates the amplitude, phase, or polarization of light in two dimensions, typically in the form of an array. SLMs are...

Spectral domain optical coherence tomography is an imaging technique used in medical diagnostics, particularly in ophthalmology, to visualize and analyze the internal structures of biological...

Radiation emitted when a quantum mechanical system drops spontaneously from an excited level to a lower level. This radiation is emitted according to the laws of probability without regard to the...

The probability that an atom in one state will move spontaneously to a lower state within a given unit of time.

A sputtering target is a solid material used in the process of physical vapor deposition (PVD), specifically sputtering. Sputtering targets are typically made of metals, metal alloys, or compounds...

A wave that changes from one amplitude to the other in a short time compared with the wavelength.

A technique for creating optimal performance in a system by producing a specific beam irradiance distribution, usually through the use of geometric optics. A common design involves the use of ray...