Photonics Dictionary: A

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...

A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or...

A mode of data transmission whereby each bit of information is generated separately, with some stop/start code to indicate the interval between bits.

Compilation of the Air Force Cambridge Research Laboratories that contains values of the line parameters of the 1-0 bands of 12C16O. Because of the high accuracy of this record, calculated spectra...

Formulaic compensation to correct laser ranging data for the effects of horizontal refractivity gradients; it requires the horizontal pressure and temperature gradient at laser sites, which are...

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...

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...

The real part of the axial propagation constant for a particular mode. The attenuation coefficient for the mode power is twice the attenuation constant.

In fiber optics, the limitation on performance imposed by the amplitude of a received signal rather than distortion.

An attenuator is an electronic or optical device used to reduce the power or intensity of a signal without significantly affecting its waveform or other characteristics. Attenuators are commonly used...

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...

The energy analysis of electrons released in a secondary step following initial excitation or ionization.

Augmented reality (AR) is a technology that integrates digital information, typically in the form of computer-generated graphics, images, or data, with the real-world environment in real-time. AR...

The green line, in the spectrum of the aurora borealis, that has a wavelength of 5577 Å; it is caused by a forbidden transition in oxygen.

A device for automatic exposure control in which a motor-driven diaphragm adjusts the aperture in response to a signal from a photocell detecting ambient light.

A spectrograph in which the refracted beam returns almost along the path traveled by the incident beam, and is brought to a focus by the lens that collimates the incident beam.

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 signal-averaging device that improves signal-to-noise ratio by comparing a sampled signal with a time-delayed form of itself.

Autofluorescence refers to the natural emission of fluorescence exhibited by certain biological structures or molecules when exposed to light. Unlike fluorescence that results from the application of...

A CCD sensor that provides feedback to the motion control system for a telescope, allowing the telescope to follow a particular object or section of sky automatically.

Automated optical inspection (AOI) is a technology used in manufacturing processes, particularly in electronics, to automatically inspect and detect defects or anomalies in products. AOI systems use...

A system for automatic industrial process control or measurement, consisting of an optical module for image acquisition, a segmentation processor to isolate the image from its background, and an...

In fiber optics, the use of a detector to study the range of refractive indices achieved at various wavelengths. This information is calculated electronically to establish the divergence between...

The photographic recording of the distribution and location of radioactive substances found in a specimen. The record formed is the autoradiograph.

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...

A lens aberration that causes axial light rays having different wavelengths to focus at various points along the axis.

A vapor-phase oxidation process for fabricating graded-index optical fibers. It differs from outside vapor phase deposition in that the preform is developed radially rather than longitudinally. An...

An axicon is a type of optical component characterized by its conical shape and its ability to transform a collimated Gaussian beam of light into a ring-shaped beam with a gradually increasing...

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)....