Photonics Dictionary

absolute (kelvin degrees), absorption, acoustic, alpha particle, analog, anode, ampere, amplitude, area, atomic, atomic mass, Helmholtz free energy, mass number, nucleon number

analog to analog, anti-aliasing (AA optical filter e.g. low pass filter), approximate absolute temperature, atomic absorption

ablation threshold

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

absorption

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

absorption coefficient, absorption cross section

The transition cross section constant coefficient which defines the transition probability of absorption from ground to a higher level within a given atomic or molecular species. The transition...

absorption line

The wavelength or frequency corresponding to an absorption resonance with a given molecular or atomic species. The line spectrum will vary with the element as well as the molecular compound.

absorption peak

An absorption peak refers to a sharp increase or spike in the absorption of electromagnetic radiation at a particular wavelength or energy level. It is a distinctive feature in the absorption...

actinide

Any of a series of radioactive elements with atomic numbers ranging from 89 to 103.

activity

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...

AES

Auger electron spectroscopy; atomic emission spectrometry

AFM

atomic force microscope

AFS

atomic fluorescence spectroscopy

ALD

atomic layer deposition

ALE

atomic layer epitaxy

alpha particle

A positively charged particle emitted from the nucleus of an unstable isotope, characterized by two protons and two neutrons. Quantitatively, the equivalent of a helium atom's nucleus.

AMU

atomic mass unit

angstrom

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...

antiferromagnetism

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

APS

active pixel sensor; active pixel system; Advanced Photon Source; American Physical Society; atom probe spectroscopy; autocorrelated photon spectroscopy

Abbe refractometer; acoustic radiometer; acoustic resonance; active region; alpha ray; amplitude ratio; antireflective; aperture ratio; applied research; argon; aspect ratio; atomic reactor; augmented reality

atomic time

atom optics

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...

atomic absorption spectrometer

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...

atomic absorption spectroscopy

The analysis of the atomic structure of a sample by means of a source radiation that is absorbed and emitted by the sample with lines corresponding to the number and arrangement of atoms. Generally a...

atomic clock

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...

atomic emission spectrometry

Spectrometric analysis of the distinct and characteristic spectra of atoms of elements. The atoms are energized to emit radiant energy, which, when dispersed by a prism or diffraction grating,...

atomic fluorescence spectroscopy