Photonics Dictionary

Active optics refers to a technology used in telescopes and other optical instruments to improve the quality of images by dynamically adjusting the shape of optical components, such as mirrors, in...

An active-cavity radiometer is a highly sensitive instrument used to measure radiant energy (power per unit area), often in the form of electromagnetic radiation. The key features of an active-cavity...

An actuator is a mechanical or electromechanical device that is responsible for moving or controlling a mechanism or system. It converts various forms of energy (such as electrical, hydraulic,...

Acutance refers to the perceived sharpness of an image in terms of the contrast of edges, rather than the resolution of fine details. It relates to how well-defined and crisp edges appear in a...

Visual adaptation refers to the process by which the visual system adjusts to changes in the environment or stimuli over time. It allows the eyes to maintain sensitivity and perception under varying...

An optical adapter typically refers to a device or component used in optical systems to facilitate connections between different types of optical fibers, connectors, or interfaces. Here are a few...

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 adaptometer is an instrument used to assess the adaptation of the human eye's sensitivity to changes in ambient light conditions. It typically involves exposing the eye to controlled levels of...

Additive color mixing refers to the process of creating colors by combining different wavelengths of light. In this system, red, green, and blue (RGB) are considered primary colors. By mixing varying...

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: ...

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...

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...

Optical thin film adhesion specifically refers to the adhesion properties of thin films used in optical applications. Here’s a detailed definition: Thin film materials: Optical thin films...

Adiabatic laser colorimetry is a technique used to measure the color of materials based on the principle of adiabatic demagnetization. Principle: Adiabatic laser colorimetry relies on the...

A process during which no heat enters or leaves the system.

The advanced communication technology satellite (ACTS) was a program developed by NASA (National Aeronautics and Space Administration) in the United States to demonstrate and advance satellite...

Photographing of terrain on the ground and objects in the air by cameras mounted in aircraft; utilized in satellites, multispectral scanning and intricate data handling systems.

The use of optical or electronic recording systems to extract information from the terrain, while aloft, for reconnaissance applications.

A two-phase system consisting of dispersed liquid or solid particles in a gas; examples include dust, smoke and clouds.

An optical system with object and image points at infinity. Literally, "without a focal length."

That image remaining on the detector after the primary stimulus has been removed. In the visual system, the after-image commonly appears as the complementary color of the primary stimulus.

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...

The central peak (including everything interior to the first zero or dark ring) of the focal diffraction pattern of a uniformly irradiated, aberration-free circular optical element or system.

Alternating current (AC) is an electrical current in which the direction of flow of electric charge periodically reverses. This reversal occurs at regular intervals, typically in a sinusoidal...

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...

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...

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 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...

Analog adaptive resonance theory (AART) is a neural network model within the broader framework of adaptive resonance theory (ART), which was introduced by Stephen Grossberg. ART is a cognitive and...

Analog-to-analog (AA) refers to the process or system that involves the conversion or transmission of analog signals from one form to another, without converting them into digital signals at any...

Analog-to-digital (A/D) is a process that converts continuous analog signals into discrete digital signals. This process coverts analog signals continuously, which vary smoothly over time, into a...

A term used to denote a difference in magnification along mutually perpendicular meridians. Anamorphic systems are basically image-distorting systems, such as those used in motion pictures, that...

A state in which an image is distorted by an optical system.

A system used for measuring direct solar radiation.

The angular spectrum approach is a mathematical and computational technique used in the field of optics to analyze and simulate the propagation of optical waves, particularly in the context of wave...

The measured planar or solid angle of related aspects of an optical system with respect to an optical axis.

Anisotropy refers to the property of exhibiting different values or characteristics when measured in different directions. In various fields, including physics, materials science, and geology,...

The elimination of magnetic moments and decrease in magnetic susceptibility with a decrease in temperature due to the equal power of atomic magnets.

An antigen is any substance that is capable of triggering an immune response in an organism. Antigens are typically proteins or large polysaccharides, although other types of molecules can also act...

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

An APD detector, or avalanche photodiode detector, is a type of photodetector used to detect light or optical signals by converting incoming photons into electrical current. It operates based on the...

The second adjustable iris diaphragm in an optical system. In the common microscope condenser system, it usually is located beneath the substage condenser on a transmitted light microscope. When the...

Aplanatic points refer to specific points in an optical system where certain aberrations, such as spherical aberration or coma, are minimized or eliminated. In an optical system, aberrations are...

An aplanatic surface is an optical surface that is specifically designed or shaped to minimize spherical aberration and coma. Spherical aberration is an optical aberration that occurs when light rays...