Photonics Dictionary

Magnification that is above the level of maximum useful magnification and does not contribute useful resolving power. In a visual telescope, empty magnification is any in excess of 20 D, where D =...

Epitaxial deposition is a process used in semiconductor manufacturing and materials science to grow a thin crystalline layer, known as an epitaxial layer, on a substrate. The term epitaxial refers to...

A densitometer having a receiver that indicates when a desired radiation level has been attained.

An optical fiber that can be used to amplify an optical input. Erbium rare earth ions are added to the fiber core material as a dopant in typical levels of a few hundred parts per million. The fiber...

An event-based image sensor, also known as a dynamic vision sensor (DVS), is a type of digital imaging device designed to capture visual information in a highly efficient and unique way compared to...

The ratio of the intensities of two specified spectral lines of a source having vastly different excitation energies. This ratio indicates the level of excitation energy in the source.

The amount of energy required to raise the energy level of an atom; a necessity if the atom is to radiate energy. High excitation potential is the amount of energy in the upper state of the...

A fiber optic sensor is a device that uses optical fibers to detect and measure physical, chemical, biological, or environmental parameters. Unlike traditional electrical sensors, fiber optic sensors...

A fiber-coupled LED (light-emitting diode) refers to an LED device that is optically coupled to an optical fiber for the purpose of efficient light transmission. In this configuration, the LED serves...

Fluorescence microscopy is a specialized optical imaging technique used in biology, chemistry, and materials science to visualize and study specimens that exhibit fluorescence. Fluorescence is the...

A fluorescent screen refers to a phosphorescent or fluorescent-coated surface that emits visible light when exposed to other forms of electromagnetic radiation, such as x-rays or ultraviolet light....

A fiber optic device that uses a HeNe laser, beamsplitter, monochromator and photomultiplier to detect trace levels of chemicals and viruses in samples inside or outside the body.

A special laser glass made primarily of fluoride compounds that exhibits extremely low refractive index and allows greater levels of energy to be generated as the laser beam passes through the...

Förster resonance energy transfer (FRET) is a mechanism describing the transfer of energy between two closely spaced fluorescent molecules. This phenomenon is named after the German scientist...

The phenomenon whereby an electron within a band absorbs radiation by transferring from a low-energy level to an empty high-energy level.

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures changes in hemoglobin concentration in the brain. It utilizes near-infrared light to penetrate the...

Fused quartz and silica are closely related materials, both composed primarily of silicon dioxide (SiO2), but they are produced through different manufacturing processes and have distinct properties...

A GaAlAs laser is a type of semiconductor laser diode that emits light in the near-infrared region of the electromagnetic spectrum. It is composed of layers of gallium, aluminum, and arsenic, hence...

Gallium nitride (GaN) is a compound made up of gallium (Ga) and nitrogen (N). It is a wide-bandgap semiconductor material that exhibits unique electrical and optical properties. Gallium nitride is...

The spontaneous emittance of electromagnetic radiation by the nucleus of certain radioactive elements during their quantum transition between two energy levels. The radiation emitted has a wavelength...

GaN (gallium nitride) distributed feedback (DFB) lasers refer to a specific type of semiconductor laser based on Gallium Nitride materials and designed with a distributed feedback structure. These...

One of the first lasers to find practical application. Generally, the pumping mechanism is an electric discharge, although some high-power forms employ chemical reaction or gas compression and...

An acronym of gamma ray amplification by stimulated emission of radiation. It is a gamma ray laser that operates between energy levels established by metastable isomeric transitions in the nucleus.

In image processing, the range of available gray levels. In an 8-bit system, the gray scale contains values from 0 to 255.

An image consisting of an array of pixels that can have more than two values (black and white). Typically, up to 16 levels are possible per pixel.

Also known as ground level. The lowest energy level of an atom or atomic system. A material in the ground state is not capable of emitting optical radiation. All other states are called excited...

Triggering a laser at a predetermined time by pumping it to a level just below its threshold and then using an auxiliary source that quickly pumps it above threshold. Means of achieving it in laser...

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

High dynamic range (HDR) refers to a technology that allows for a broader and more dynamic range of luminosity in visual content, such as images or videos. It is particularly associated with displays...

Optical fiber in which the attenuation exceeds the normally acceptable level for long-haul or data communications use.

A high-sensitivity camera is a type of camera designed to perform well in low light conditions, capturing clear and detailed images with minimal noise. These cameras typically feature advanced sensor...

Histochemical staining is a laboratory technique used in biology and medicine to visualize specific chemical components within biological tissues. This technique involves the application of various...

Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs at the cellular and subcellular levels. It is a field that focuses on the...

A junction between semiconductors that differ in their doping level conductivities but not in their atomic or alloy compositions.

Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the electromagnetic spectrum. Unlike traditional imaging systems that record only a few...

Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a hyperspectral imaging system. In hyperspectral imaging, the electromagnetic spectrum is...

An image intensifier, also known as an image intensification tube or image intensification device, is a specialized electronic device used to amplify low-light-level images to make them visible to...

An infrared camera, also known as a thermal imaging camera or IR camera, is a device that captures and visualizes the infrared radiation emitted by objects, revealing temperature variations across...

An infrared detector is a device that is used to detect and measure infrared radiation, which lies beyond the visible spectrum of light. These detectors are utilized in various applications,...

A countermeasure used against heat seeking missiles to reduce their effectiveness. Normally it involves the emittance of infrared radiation at a level that will overload the missiles' detectors.

An InGaAs photodiode refers to a photodetector device that is constructed using a semiconductor material composed of a combination of indium (In), gallium (Ga), and arsenic (As). The term InGaAs...

Instantaneous field of view (iFOV) is a term commonly used in the context of remote sensing, imaging systems, and optical instruments. It refers to the specific portion of a scene that an optical...

Integration time, in the context of optics, imaging systems, and sensor technology, refers to the duration over which a sensor collects and accumulates incoming light or signal. It is a crucial...