Photonics Dictionary: S

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...

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...

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 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...

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

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 mechanical or electronic device used to control the amount of time that a light-sensitive material is exposed to radiation.

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

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...

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...

The simulation of solar radiation in the infrared and ultraviolet spectrum for the analysis of extraterrestrial sunlight and its effects on spacecraft, materials and components.

1. The reduction in the developable density of a photographic emulsion that has been extremely overexposed. 2. In a laser system, damage resulting from ultraviolet radiation that degrades the lasing...

1. Generally, an emulsion mask having a clean annular region in an otherwise opaque region. It is designed to eliminate undesired information. 2. A pinhole in a metal plate, placed at a focal plane...

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...

Any pyrheliometer that has a filter placed over its sensor to limit the range of solar radiation it will detect; used to determine the distribution of solar radiation over its visible and into its...

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic spectral response of a material or object across different wavelengths of the...

An automatic scanning instrument that is used to study a substance's fluorescence over a wide range of wavelengths. It consists of a radiation source, a grating that functions as the monochromator in...

Characteristic of the relationship between photoelectric activity and the wavelength of incident radiation.

A spectroradiometer is a device used to measure the intensity of light at different wavelengths across the electromagnetic spectrum. It provides a detailed spectral distribution of light, breaking...

In a general sense, any one of a class of instruments used to disperse radiation, visible or invisible, into its component wavelengths and for determining or measuring the resultant spectrum. In a...

Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves measuring and analyzing how different materials absorb, emit, or scatter light,...

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...

A synchrotron is a type of particle accelerator that uses magnetic fields to steer charged particles, typically electrons or positrons, in a closed, circular or elliptical path. The name synchrotron...

Radiation emitted by electrons when they travel in circular orbits at speeds close to that of light. Synchrotron radiation occurs in the x-ray and ultraviolet regions of the spectrum. Once considered...