Photonics Dictionary: A

Any system of time measurement that is based on atomic resonances. The transition times between the hyperfine levels of cesium-133 have been accepted as the international standard.

A reflecting prism that inverts the image. The image is reflected four times internally and emitted laterally. The prism is cut normal to the optical axis while the image is internally reflected from...

An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms, it measures acceleration. Accelerometers are widely used in various...

Stimulating light used for the production of energy through photosynthesis, solar cell or other light senstitive device.

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

1. Synonymous with radioactivity. The intensity of a radioactive source illustrated as the number of atoms disintegrating in unit time, or as the number of scintillations or other effects observed...

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...

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.

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...

A system in which a sequence of direct measurements of the target position is fed into a tracking filter that may produce refined estimates of past, present and future target positions.

The coefficient Å in Angstrom's formula for the dispersing coefficient for dust present in the atmosphere. The formula is expressed as S × Ål-B where l represents wavelength and B...

An angstrom, symbolized by the Ångström or Å, is a unit of length used to express atomic and molecular dimensions. It is equal to 0.1 nanometers or 1 × 10-10 meters. The...

Angular deviation from the optimum alignment of source to optical waveguide, waveguide to waveguide, or waveguide to detector, resulting in a loss of optical power.

A laser radar application in which a sequence of direct measurements of target position is fed into a tracking filter to produce refined estimates of both present and future target positions.

Gamma ray radiation released when matter and antimatter, such as electron and positron, unite and eliminate each other, transforming completely into energy. The resulting gamma ray spectrum depends...

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...

The visual perception of motion when fixed stimuli are exposed in rapid temporal and spatial succession.

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...

In the discharge of a vacuum tube, the narrow, nonluminous region that sometimes may be found between the cathode and its glow.

The unit generally used to express distances within the solar system, and sometimes to measure interstellar distances. Technically, one astronomical unit is the mean distance between the Earth and...

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...

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...

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

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...

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...

In a pulsed laser, the pulse energy in joules times the repetition rate in hertz.