Photonics Dictionary: A

The angular subtense of the field of view in the image space of a telescope, as differentiated from that in the object space (the true field).

A departure from ideal paraxial imaging behavior. The distortion of an optical field wavefront as it is propagated through the elements of an optical system. The field distortion is due to the...

The transfer of energy from an incident electromagnetic energy field with wavelength or frequency to an atomic or molecular medium.

The optical reconstruction of image information contained in a sound field. First the diffraction pattern, formed by an object irradiated by ultrasonic rays, interferes with a mutually coherent...

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

A compound lens combination whose astigmatic difference is zero for one or more off-axis zones in the image plane. In such a lens the other aberrations are sufficiently well-corrected to yield...

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...

Anisotropic is a term used to describe a material or substance that exhibits different properties or behaviors in different directions. In other words, the physical or mechanical characteristics of...

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,...

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 amplitude, polarization and phase contained in the field distribution over the aperture.

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 apochromat, often referred to as an apochromatic lens or apochromatic objective, is a type of optical system designed to minimize chromatic aberration. Chromatic aberration occurs when different...

An arc flash is a sudden release of electrical energy due to an electric arc — a continuous, high-current discharge of electricity between conductors or from a conductor to ground. Arc flashes...

Area scan, in the context of imaging and cameras, refers to a method of capturing an entire two-dimensional image in a single snapshot or exposure. Unlike line scan, which captures images one line at...

An aspheric lens is a type of lens whose surface profiles deviate from the traditional spherical shape. Unlike spherical lenses, which have a constant curvature across their surfaces, aspheric lenses...

A gas, such as oxygen, that improves the speed and efficiency of a laser cutter or welder when applied to the work surface, or an inert gas, such as argon, that helps to clean or shield the work...

An astronomical telescope is a type of optical instrument designed to gather and magnify light from distant celestial objects for observation and analysis. It typically consists of two main optical...

An atomic clock is a highly precise timekeeping device that uses the vibrations or oscillations of atoms as a reference for measuring time. The most common type of atomic clock uses the vibrations of...

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples. It is particularly useful for analyzing solid and liquid samples without...

Attenuation refers to the gradual loss or reduction of intensity, force, or magnitude of a particular property as it propagates through a medium or travels over a distance. This concept is prevalent...

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...

Attosecond-pump attosecond-probe spectroscopy (APAP) is an advanced technique in ultrafast spectroscopy that allows scientists to study the dynamics of electronic processes occurring on extremely...

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 receiver for optical communications systems consisting of a symmetric binary, pulse-code-modulated transmitter, a log-normal channel and an array of independent photocounting detectors that yield...

Azadioxatriangulenium is a type of organic compound with a unique triangular molecular structure. It is often abbreviated as ADOTA. This compound belongs to the class of polycyclic aromatic...

Azimuthal polarization refers to a specific polarization state of light where the electric field vector of the electromagnetic wave points along the azimuthal direction (around the propagation axis)....