Photonics Dictionary

A type of spectroscopy used extensively in the analysis of biological samples. Because most biologically synthesized molecules, such as proteins, are optically active, circular dichroism spectroscopy...

A device used for the comparison of spectra used, in turn, for the comparison of elements, such as the absorption lines in the spectra of stars and the spectra of elements in the stars being observed.

The spectrographic analysis of matter that is in a cooled state. Generally, a mechanical refrigerator is used to lower the temperature of the sample, allowing isolation and study of the sample and...

A system that applies a crystal as a diffracting agent to photograph the spectrum.

A device designed to measure crystal properties by analysis of crystal diffraction.

A small mass spectrometer, with a limited mass range, equipped with an analyzer to generate a cycloidal-path beam of the sample.

The measurement of the spectrum bands formed by a spectroscopic sample, based on the differences between the sample and the reference cell it is placed in.

A spectrograph that uses a diffraction grating as its dispersive element in place of a prism, and yields greater resolving power, more dispersion and a linear spectrum.

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties of materials, particularly in the field of spectroscopy. Unlike traditional...

A small handheld instrument consisting of a slit and collimator that feeds light into a small direct-vision dispersing prism. The eye is placed behind the prism to observe the spectrum of a colored...

A spectroscope having a divided circle and a means for the rapid reversal of prisms for the measurement of refractive index of the prism for a specific wavelength.

A spectrophotometer that measures the amount of ozone in the atmosphere through a comparison of solar energy at two wavelengths in the ozone's absorption band. This comparison is achieved by...

A spectrophotometer in which the beam emitted by the radiation source is split into beams that travel through the sample and a reference cell and are subsequently recombined to fall on the detector....

A mass spectrometer utilizing both radial electrostatic and magnetic field analyzers to improve the focusing and increase resolution.

Spectrophotometry in which radiation of two separate wavelengths, usually one in an absorption band and the other not, pass through the specimen. The resulting data allows correction for attenuation...

A spectroscopic technique used to display the intensity of an optical pulse as functions of time and frequency simultaneously.

The use of a krypton laser system for the measurement of small molecules aligned by an electric field, by analyzing the absorption of linearly polarized light.

The spectroscopic analysis of interference patterns using an electronic imaging tube with a Fabry-Perot interferometer to record the fringes.

A type of modulation spectroscopy that measures spectral reflectance or transmittance changes induced by applying a perturbing electric field. It can be performed in contactless modes with no special...

The theory and interpretation of spectra produced by the electron emissions of substances after their irradiation by x-rays.

A type of electromodulation that measures changes in spectral reflectance.

A study of the energies and wavelengths of radiation emitted by atoms and molecules when particular physical conditions are applied to them.

The spectroscopic analysis of interference patterns using a monochannel spectrometer, spectrograph or multichannel spectrometer with a Fabry-Perot interferometer to record the fringes.

A fiber optic spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to transmit light from a source to a spectrometer unit, where the light is...

A spectrophotometer that makes use of filters to isolate narrow bands of the spectrum.

A technique in photometry that uses an oxyhydrogen or oxyacetylene flame to optically excite a solution containing the sample to be analyzed.

The procedure applied to flame-excited line emissions to determine spectra and wavelengths.

The study of the reflection or transmission properties of specimens as a function of wavelength after they have been excited by flame-analysis techniques.

The study of flames by means of a laser emitting blue light and a spectrometer to measure the green fluorescence created by the flame chemistry.

The study and interpretation of the spectra of substances after they have absorbed the radiant energy emitted by a brief, intense light source.

A technique developed to measure the molecular weight of macromolecules by analyzing the spontaneous fluctuations that occur in the inherent thermodynamic concentration of solute molecules in a...

A powerful method, referred to as FCS, for determining the average diffusion coefficients of fluorescent molecules in solution or membranes. FCS measurements rely on recording the transition of...

The spectroscopic study of radiation emitted by the process of fluorescence.

An instrument using a Michelson interferometer, a beamsplitter, two plane mirrors and a detector to give Fourier analysis of the detector signal to provide the desired spectrum.

FTIR (Fourier transform infrared) spectrometer is a powerful analytical instrument used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas sample. It operates based...

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures changes in hemoglobin concentration in the brain. It utilizes near-infrared light to penetrate the...

An instrument used to detect and measure the energy distribution of gamma rays. It has been used to chart the radioactivity at the lunar surface.

A device similar to the ordinary spectrophotometer but containing particular modifications to provide for the comparison of two sources.

A spectrograph having glass as its refracting component and used in cases where speed and high dispersion are not required. The glass material has a range of about 3700 to 8000 Å.

A spectrometer that uses a grating to diffract light into specific wavelengths.

A spectroscope having a diffraction grating for the resolution of light of various wavelengths.

A visual spectrophotometer with a rhomb located directly before the entrance aperture of a constant-deviation spectrophotometer.

A spectrophotometer having a prism or, more frequently, a grating for the study and recording of infrared spectra. It usually consists of a radiation source such as a Nernst glower, a monochromator,...

The measurement of the ability of matter to absorb, transmit or reflect infrared radiation and the relating of the resultant data to chemical structure.

Also known as the Bragg spectrometer. A system used for the x-ray analysis of crystal structure. In the instrument, a homogeneous beam of x-rays is directed on the known face of a crystal and the...

A spectroscopic technique in which an excitation band absorbs laser energy resulting in an electronic transition. The isotopic species may then be measured using a time of flight mass spectrometer....

A visual, single-unit spectrophotometer with a biprism and a Wollaston prism. The Wollaston prism polarizes coincident images of the two halves of the entrance aperture.