Photonics Dictionary: A

The creation of a chemical reaction in a substance when radiation is directed to it.

A device that measures the intensity of photochemically active radiation, particularly from the sun. One form of this instrument determines the fluorescence initiated by the radiation.

imaging system which clearly shows the IR signals in the field of view as well as ambient environment

That layer in a semiconductor injection laser or light-emitting diode that provides optical gain.

A material that produces stimulated emission during the process of amplification with a laser system.

The layer of material in a laser diode from which the optical radiation is emitted; light producing region

The transport of molecules in a cell which requires the use of a cell's internal energy. The energy used in the cell may be ATP as a primary transport or an electrochemical gradient give as the...

When applied to LCD grids, the active matrix is a means of supplying power to pixels by use of a transistor and capacitor. The transistor functions with leads in operation with its respective row and...

An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two thin-film transistors (TFTs) to control the on-current at each OLED cell or...

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

An apparatus used to determine the degree of adaptation of the eye under different conditions.

Process in which two or more lights are combined by superposition.

Additive manufacturing (AM), also known as 3D printing, is a manufacturing process that involves creating three-dimensional objects by adding material layer by layer. This is in contrast to...

The luminance of a mixture of lights is the sum of the luminances of the component lights in the mixture.

In display technology, an expression of resolution given by the number of pixels in both the horizontal and the vertical axes of a cathode-ray tube or similar device.

A chemical placed in a solution that will indicate when an excess of a substance or ion has been reached by coloring the precipitate after the chemical itself has been totally adsorbed.

Advanced driver assistance systems (ADAS) refers to a set of safety features and technologies designed to assist drivers in the driving process and enhance overall vehicle safety. These systems use...

An aerial reconnaissance system that can transmit, in near real time, image data recorded by IR and visual-spectrum sensors, providing day, night and foul-weather intelligence.

A glow discharge lamp consisting of a cold cathode and a mixture of inert gases. The intensity of illumination varies with the applied signal voltage. This lamp was commonly used as a source of...

The luminosity that remains in a rarefied gas after an electrodeless discharge has traversed the gas.

A visible laser beam generated coaxially with an infrared or other invisible laser beam to aid in its positioning.

An instrument designed to measure angles in azimuth; used in general topographic work and military gunnery.

A support device in which a column or chamber of air permits the free travel of a mobile part. In optical mounting and positioning equipment, air bearings are of two types, linear or rotary,...

Diffuse light emitted by the atmosphere due to the excitation of particles of atmospheric gas. These excited particles release light that is visible from Earth as a faint luminescence in the night...

A host crystal for chromium that emits pulsed or continuous-wave laser light, tunable from about 720 to 790 nm.

An alexandrite laser is a solid-state laser that utilizes a synthetic crystal made from the rare earth element alexandrite (BeAl2O4:Cr3+). This crystal is capable of emitting laser light in the...

An optical tooling instrument consisting of an objective lens, a focusing lens, an optical micrometer, a reticle and an eyepiece. The alignment telescope projects a precise line of sight to which a...

Any fluorescence in which the wavelength of the emitted light differs from that of the absorbed light.

A 2-million W, 2.7-µm-wavelength hydrogen-fluoride laser used as a directed energy weapon.

A positively charged particle emitted from the nucleus of an unstable isotope, characterized by two protons and two neutrons. Quantitatively, the equivalent of a helium atom's nucleus.

A luminous display of numbers and the letters of the alphabet.

A type of telescope mount that permits direct azimuth and elevation adjustments.

A cathode-ray tube having a screen that is coated on the back with a thin film of aluminum, which serves to intensify the propagation of light.

The process of applying a film of aluminum to a surface, usually by evaporation in a vacuum.

A form of high-power microscope objective.

Also known as roof prism. A type of prism designed by G.B. Amici. It consists of a roof edge produced upon the long reflecting face of a right-angle prism. Used as an erecting system in elbow and...

In digital data transmission, the representation of a bit by change in amplitude of the outgoing signal. Amplitude shift keying (ASK) is less sensitive than phase-shift keying, but can tolerate...

A type of fiber optic sensor that detects alteration in position, distance, pressure, liquid level or temperature by transmitting light across a gap to a reflector; a change in the light returned to...