Photonics Dictionary: A

In present usage, especially for spectroscopic identification, an arc between electrodes that serves as a radiation source. Gas tubes that contain mercury vapor and mixtures of helium, neon and argon...

An Abbe condenser is a type of optical component used in microscopy to enhance the illumination of the specimen. Named after the German physicist Ernst Abbe, who developed it in the 19th century, the...

Image of a uniform source through the sample of a microscope image system. Light from the sample plane is reimaged by the objective into the image plane.

An Abbe refractometer is a scientific instrument used to measure the refractive index of liquids and solids. Named after the German physicist Ernst Abbe, this device operates on the principle of...

An abridged spectrophotometer refers to a simplified or compact version of a traditional spectrophotometer, which is a scientific instrument used to measure the intensity of light at different...

Absolute colorimetric refers to a color management rendering intent used in color profiles and conversion processes, particularly in the context of printing and digital imaging. Absolute...

The absolute luminance threshold is the lowest luminance level of a light source or illuminated object that can be detected by the human eye under specific conditions. This threshold represents the...

Absolute white is a term used in color science and imaging to describe a reference white point that represents the brightest, most neutral white achievable. It serves as a standard for measuring and...

An absorbing wedge is an optical device used to control the intensity of light passing through it by absorbing a portion of the light. It is typically used in experiments and optical systems where...

Absorption is the process by which a material takes in energy from electromagnetic radiation (such as light, heat, or sound) and converts it to other forms of energy, typically internal energy (such...

Absorption spectroscopy is a fundamental analytical technique used to study the interaction between electromagnetic radiation and matter. It involves measuring the absorption of light by a sample...

Accessible emission typically refers to the portion of emitted radiation (light, particles, etc.) from a source that can be effectively detected, measured, or utilized by an observer or device. This...

An acousto-optic deflector (AOD) is a type of device that utilizes the acousto-optic effect to control the direction of light beams. It operates by modulating the refractive index of an optically...

An acousto-optic modulator (AOM) is a device that utilizes the acousto-optic effect to modulate the amplitude, phase, frequency, or polarization of a laser beam or other coherent light source. It...

Actinochemistry refers to the branch of chemistry that studies the chemical effects of radiation, particularly light, on substances and chemical reactions. Here are the key aspects of...

An active infrared (IR) system is a type of technology that uses infrared radiation actively emitted and detected by sensors for various purposes. Here are the key features and applications of active...

In the context of semiconductors and electronics, the active layer is the part of a semiconductor device where the essential electronic activities take place. This includes the movement and...

An active medium is a material or substance used in various optical devices and systems, where it plays a critical role in amplifying light or producing laser beams through the process of stimulated...

The additive color process refers to the method of creating color by combining different wavelengths of light. This process is fundamental in various applications, particularly in: ...

The additivity of luminance refers to a principle in visual perception and color theory where the perceived brightness of a combination of light sources or colors is the sum of the brightness of each...

Optical addressability refers to the capability to control or manipulate individual elements that emit or modulate light (such as pixels in a display or light sources in an optical network) using...

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...

Agri-photonics refers to the application of photonics technologies in agriculture. Photonics involves the generation, manipulation, and detection of light and other forms of radiant energy whose...

An instrument that reads alphabetic, numerical and special characters by means of a photosensor that measures the varying intensity of the characters reflected from a light source.

Light present in the environment around a detecting or interpreting device, especially a machine vision system, and generated from outside sources. Such light must be treated as noise by the vision...

An ammonia maser is a device that amplifies microwave radiation using ammonia gas molecules in a process analogous to how lasers amplify visible light through stimulated emission of radiation. The...

A light source that emits an uneven distribution of radiant energy through the visible range.

A bright spot or point, due to Fresnel diffraction, that appears at the center of the shadow of a circular object in light originating from a point source. Also referred to as a Fresnel spot or...

An argon-fluoride (ArF) excimer laser is a type of ultraviolet laser that operates using a mixture of argon and fluorine gases. Excimer lasers are a class of gas lasers that emit light in the UV...

A point source of light used for the test and evaluation of image quality. May be a backlit pinhole in an otherwise opaque sheet placed at an appropriately large distance from the lens being tested.

A cylindrical lens that may be rotated to distort a bundle of light originating at a point source, to form a line image.

An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

Attosecond photonics sources refer to devices or systems that generate extremely short pulses of light on the order of attoseconds (1 attosecond = 10-18 seconds). These ultrafast light pulses are in...

An autocollimator is an optical instrument used for measuring small angular deviations with high precision. It operates on the principle of autocollimation, where a light source is directed onto a...

A means of adjusting the sharpness of an image automatically, with a sensor for estimating distance or contrast and a drive mechanism to adjust the lens. Active systems generate a light source to...