Photonics Dictionary: A

Method for studying absorption coefficients of low-loss materials, in which a sample is allowed to come to thermal equilibrium with its surrounding blackened enclosure. The sample is irradiated with...

An alexandrite laser is a solid-state laser that utilizes a synthetic crystal made from the rare earth element alexandrite (BeAl2O4:Cr3+). This crystal is capable of emitting laser light in the...

A laser, usually employing helium-neon or other gases as the active medium, used for alignment in industrial applications.

A 2-million W, 2.7-µm-wavelength hydrogen-fluoride laser used as a directed energy weapon.

gas laser using ionized argon as the active medium and applying electronic excitation in order to produce the laser light

Designed for the function of optical wavefront analysis. Shack-Hartmann camera aberration sensors use a lens array to image the wavefront to the CCD image plane. Live feedback may be applied through...

The minimum energy required to induce atomic and molecular separation or displacement due to incident intense laser irradiation.

The present radiation level within a laser or electromagnetic radiation operating area.

A system designed with a laser as a light source and a means for producing sound waves extending beyond 100 MHz to deflect light efficiently.

A device that varies the amplitude and phase of a light beam; e.g., from a laser or by sound waves. Also known as a Bragg cell.

An acousto-optic modulator (AOM) is a device that utilizes the interaction between sound waves and light waves to modulate or control the intensity, frequency, phase, or direction of laser beams. It...

That layer in a semiconductor injection laser or light-emitting diode that provides optical gain.

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

The layer of material in a laser diode from which the optical radiation is emitted; light producing region

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...

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...

A visible laser beam generated coaxially with an infrared or other invisible laser beam to aid in its positioning.

A host crystal for chromium that emits pulsed or continuous-wave laser light, tunable from about 720 to 790 nm.

Charged frozen pellets that are rapidly bombarded with a focused high-power laser to form a dense plasma that can be heated and sustained with neutral beams.

Broadband radiation emitted by a laser that does not transmit through the optical element. It can be removed by filtering.

In digital data transmission, the representation of a bit by change in amplitude of the outgoing signal. Amplitude shift keying (ASK) is less sensitive than phase-shift keying, but can tolerate...

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.

A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for...

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...

The plot that expresses a reaction rate vs. the reciprocal of absolute temperature. Often used to describe the thermal characteristics of laser applications such as ablation or annealing.

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...

An aspheric mirror is an optical mirror surface that deviates from the shape of a perfect sphere, having a non-spherical surface profile. Unlike traditional spherical mirrors, which have a curved...

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...

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...

Irregularities and disturbances in the atmosphere that are of particular interest because they induce random temporal and spatial phase and amplitude fluctuations that destroy the optical quality and...

The area of optics in which the wave nature of a particle is exploited to carry out very accurate interferometry and other optical techniques with atoms instead of photons. In this process, particles...

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...

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...

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

Eye blink or head movement in response to bright light. Aversion responses such as blinking are sufficient protection from less hazardous lasers, including Class 2 lasers. An eye blink can occur, at...

A method of designing lasers whereby the laser rod is cut into elliptical discs and cooled by running water over the disc surfaces. The cooling circuit decreases the radial temperature gradients in...

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)....