Photonics Dictionary: S

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

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.

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...

1. The sorting of lenses by their color. 2. In an optical system, an irradiance or brightness gradient in the image that is not present at the object.

A method of demonstration or examination using a point source illumination without the use of any projection lens between the object and its shadow, the shadow being cast on a distant screen.

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 filter that is transparent to shorter wavelengths, but opaque to longer wavelengths.

A type of fiber optic cable that emits light from its sides along its length.

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...

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...

An object that has a sinusoidal variation of luminance. Its image will have a sinusoidal variation of illuminance and the only effect of degeneration by the lens system will be to reduce the...

A laser whose output is limited to a single wavelength.

An optical waveguide in which only the lowest order bound mode, which may consist of a pair of orthogonally polarized fields, can propagate at the wavelength of interest.

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...

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...

The process of making an abrupt break in a spherical surface on a spectacle lens so that a new center of curvature is set for a portion of the lens. This has the effect of adding a prism to that...

An aperture, usually rectangular in shape, with a large length-to-width ratio, and a fixed or adjustable shape through which radiation enters or leaves an instrument. The aperture is generally small...

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...

An instrument used for viewing in low levels of illumination by means of infrared radiation. A high-aperture lens forms an image of distant objects on the photocathode of an infrared-sensitive image...

An electric discharge lamp in which the conducting vapor is that of metallic sodium instead of the usual mercury. It emits a strong yellow light of a single wavelength.

Radiation from the sun that is made up of a very wide range of wavelengths, from the long infrared to the short ultraviolet with its greatest intensity in the visible green at about 5000 Å. The...

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...

In micropositioning, a remote positioning device in which an electric current drives a movable armature mounted on an electromagnetic coil.

The relationship between different wavelengths of light generated by a source, which may affect the spectral distribution of the light as it travels great distances in space; put forth by physicist...

Spatial light interference microscopy (SLIM) is an optical microscopy technique that belongs to the category of quantitative phase imaging methods. It is designed to provide high-resolution,...

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...

Spatially offset Raman spectroscopy (SORS) is a technique that extends traditional Raman spectroscopy by incorporating measurements at different spatial offsets. This method allows for the selective...

A technique for obtaining improved resolution of images produced by large telescopes and distorted by the effects of atmospheric turbulence. Many individual exposures are recorded at high speeds by a...

Pertaining to or as a function of wavelength. Spectral quantities are evaluated at a single wavelength.

The wavelength interval in which radiant intensity is at least 50 percent of the maximum spectral value.

Average wavelength usually determined for light-transmitting devices by taking a weighted average for each wavelength of the spectral energy distribution of incident light, transmittance of the...

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...

Spectral flow cytometry is an advanced flow cytometry technique that expands the capabilities of traditional flow cytometry by utilizing spectral information from fluorochromes to enhance...

With respect to color photography, the measurement, at a given wavelength, of the way the color film modulates the radiant flux in the optical system containing the film.

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

A narrow range of emitted or absorbed wavelengths.

Ratio of the luminous flux in a beam of radiation to the spectral radiant flux in the same beam at a given wavelength.

Ratio of the radiant flux at a particular wavelength lm to that at any other wavelength l, such that both radiations produce equally intense luminous sensations. The wavelength lm is chosen so that...

The relative power emitted by a source as a function of wavelength. It determines the color-rendering properties of the source.