Photonics Dictionary

An acronym for radioactive detection, identification and computation. The term refers to the detection and measurement of the intensity of emitted nuclear radiation.

Pertaining to electromagnetic radiation, with the contributions at all wavelengths of interest weighted equally.

The energy passed on as electromagnetic radiation; e.g., radio, heat or light waves.

Infrared radiation emitted from a source that is not heated sufficiently to give off visible radiation.

The detection and analysis of naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum.

An instrument designed to collect naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum in amounts sufficient to be measured.

A photographic process using x-ray radiation or the g-rays of radioactive materials.

The study of radioactive substances and high-energy radiations such as x-rays and g-rays.

Incapable of being penetrated by any form of radiation.

Capable of being penetrated by some form of radiation.

The luminescence displayed when particular minerals are irradiated with β-rays and g-rays, after being exposed to nuclear radiation.

That element of a spectrum line in scattered radiation having a frequency equal to that of the corresponding incident radiation, due to ordinary or Rayleigh scattering.

A photographic method used to obtain an image of a subject by means of its reflectance of incident ultraviolet radiation. An ultraviolet source is used to irradiate the subject, while the reflected...

A microscope that uses a reflecting objective; often used with ultraviolet or infrared radiation.

Return of radiation by a surface, without change in wavelength. The reflection may be specular, from a smooth surface; diffuse, from a rough surface or from within the specimen; or mixed, a...

The term reflective is an adjective that describes the ability of a surface or material to reflect light or other forms of radiation. It implies the capability of bouncing back or redirecting...

The ratio of the intensity of the total radiation reflected from a surface to the total incident on that surface.

A wave of radiation that has undergone refraction.

The steady state of temperature exhibited by a material that has absorbed and emitted radiation equally.

The unit of the dose of any radiation that produces the same biological effect as one roentgen of x-ray.

Remote sensing is a method of data collection and observation where information about objects, areas, or phenomena on Earth's surface is gathered from a distance, typically using sensors onboard...

In atomic fluorescence spectroscopy, fluorescence emitted by an atom at a spectral line of a wavelength identical to that of the stimulating radiation.

The fluorescent emission spectrum emitted by certain substances following the irradiation of one of these substances with light that is of the same wavelengths as its fluorescence.

An obsolete term once used to describe a unit of radiation dosage.

A laser dye whose absorption coefficient drops at high levels of incident radiation. The phenomenon is often called bleaching.

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...

Change of the spatial distribution of a beam of radiation when it interacts with a surface or a heterogeneous medium, in which process there is no change of wavelength of the radiation.

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...

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...

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...

A photocathode that receives radiation from one side and emits a photoelectric current from the opposite side.

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

1. A generic term for detector. 2. A complete optical/mechanical/electronic system that contains some form of radiation detector.

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 that uses a blackened silver-disc reflector with a shutter to create temperature fluctuations that are proportional to the intensity of the solar radiation incident upon it. Using the...

A model that predicts laser-induced damage to thin films caused by irradiation of identical, randomly distributed film defects.

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...

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...

A substance capable of converting solar radiation into thermal energy.

A series of solar cells arranged to collect solar radiation and to generate a given amount of electrical energy.

An optical system that is designed to produce a high temperature in a specified area by the optical direction and concentration of solar radiation on that area. The system usually consists of a...

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 laser pumped by solar radiation focused by mirrors.

Plasma formed by heat radiation from the sun.