Photonics Dictionary: A

An instrument that uses optical filtration in order to measure the transmittance for a discrete range or specific number of wavelengths.

Measures the absorption or sample transmittance over a range of specified wavelengths. Sample may be placed within the device and the transmission measured to an accuracy of given percent. The...

Experimental method of measuring the transmission of a given sample as a function of the wavelength.

An instrument that photographs the spectra of an extraterrestrial object.

The process of using a spectrograph with a telescope to acquire information on an astronomical object's speed and physical characteristics.

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...

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...

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,...

The analysis of fluorescence emitted by discrete atoms, in flames, that have absorbed radiation from an external source. It is used to study the physical and chemical processes that arise from...

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...

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.

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.

A direct reading spectrograph having a photomultiplier assembly in place of a photographic plate. The output from the photomultiplier assembly is received by a microammeter or a pen recorder.

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...

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...

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...

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...

In present usage, especially for spectroscopic identification, an arc between electrodes that serves as a radiation source. Gas tubes that contain mercury vapor and mixtures of helium, neon and argon...

An atomic force microscope (AFM) is a high-resolution imaging and measurement instrument used in nanotechnology, materials science, and biology. It is a type of scanning probe microscope that...