With respect to atomic fluorescence spectroscopy, the fluorescence that is emitted by an atom at a spectral line of a wavelength that is longer than that of the stimulating radiation.

A distributed feedback laser (DFB laser) is a type of semiconductor laser diode designed to emit coherent, narrow-bandwidth...

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a...

A spectrometric instrument that detects radiation simultaneously in multiple channels, sorts it spectrally from the deep...

An array of spectral lines formed when a beam of electrons, striking a crystalline solid, is scattered. It is used in the...

For a Fabry-Perot interferometer or etalon, a value for the transmission bandwidth which can be calculated as the ratio of...

Laser optics refers to a broad category of optical components and systems designed for manipulating and controlling laser...

A filter that transmits a single spectral line emitted by a line source.

An image intensifier, also known as an image intensification tube or image intensification device, is a specialized...

Near-infrared spectroscopy (NIRS) is a non-invasive analytical technique that uses the near-infrared region of the...

1. A term used to describe the clouded appearance of an incompletely polished surface that scatters light. 2. The...

The splitting of an element's spectral line as the result of the interactions between the electron spin and the spins of...

Pertaining to or as a function of wavelength. Spectral quantities are evaluated at a single wavelength.

MWIR stands for mid-wave infrared, referring to a specific range of wavelengths within the infrared spectrum. Infrared...

A spectral phenomenon in which the degree of the photoresponse of an illuminated semiconductor is determined by the...

The basis of color vision in the human eye. Three types of cones have been identified, each having a unique spectral...

In optics, an octave typically refers to a range of frequencies or wavelengths that spans a factor of 2. In other words,...

A material that is present or added to a sample undergoing spectroscopic analysis, to serve as an intensity reference for...

Any organic substance, that when dissolved in appropriate liquid based solvents will absorb and emit electromagnetic...

A long-pass filter is an optical filter that allows longer wavelengths of light to pass through while blocking or...

In the spectral sense, an optical source that emits one or more spectrally narrow lines as opposed to a continuous spectrum....

1. A compound lens consisting of two elements. If there is an air space between the elements it is called an...

Noise over a specified frequency range, in which the spectral density is proportional to the frequency instead of being...

A night-vision device that uses one or more infrared transducers to scan a scene in the 3- to 5-µm or 8- to...

A grating that serves to provide higher resolution and dispersion than the average grating, and still has a greater free...

Ratio of the luminous flux in a beam of radiation to the spectral radiant flux in the same beam at a given wavelength.

The study of the celestial bodies, relative to x-ray emission. Satellites launched to study x-ray sources have revealed many...

Computation of tristimulus values by integrating or summing, over the visible wavelength region, the product of the relative...

An APD detector, or avalanche photodiode detector, is a type of photodetector used to detect light or optical signals by...

The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds...

A spectroradiometer is a device used to measure the intensity of light at different wavelengths across the electromagnetic...

A computer-generated, phase-and-amplitude, off-axis hologram made by a multi-exposure technique that uses three computer...

The dip or gap in the profile of a laser beam's line width when it is both homogeneously and inhomogeneously broadened. When...

The relative power emitted by a source as a function of wavelength. It determines the color-rendering properties of the...

Class of organic dyes that emit coherent radiation over a wide spectral range.

A spectrophotometer specially designed to measure spectral reflectance.

Photometry is the branch of science that deals with the measurement of light, particularly in terms of its intensity and the...

A colorimeter is a device used to measure and quantify the color characteristics of an object or a light source. It provides...

A method of spectral analysis in which some property of the sample is varied and the corresponding change is measured. The...

A spectrum formed by radiation whose energy values of the property being measured cluster about at least one discrete value,...

An early graphic scheme of colors in which saturated spectral colors are plotted around the circumference of a circle....

An etalon is an optical device that consists of two parallel reflecting surfaces separated by a precise and known distance....

An instrument that contains a spectrograph with a grating in which an array of slits, in place of a photographic plate, is...

The bands of spectral lines representing the electronic transition in a molecule.

Indicating a capability to deal with a relatively wide spectral bandwidth.

A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide...

The error inherent in spectral energy or spectrophotometric quantity due to the finite dimension of the entrance and exit...

Parallel scanning refers to a method of acquiring data or images simultaneously from multiple sources or in parallel, rather...

Spectral power distribution representing a standard source of illumination, which may be real or hypothetical.

A reflection grating is an optical component that consists of a series of closely spaced, parallel reflecting surfaces or...

An instrument in which an image of the sun is scanned by the entrance slit of a monochromator, the exit slit simultaneously...

1. A plane that forms one side of the groove ruled on a diffraction grating. 2. To form the individual grooves of a grating...

An infrared light source is a device that emits light in the infrared spectrum, which lies beyond the visible spectrum of...

Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the...

Spectral flow cytometry is an advanced flow cytometry technique that expands the capabilities of traditional flow cytometry...

Referred to as SWCNTs, these cylindrical nanostructures composed of a folded sheet of graphene can be used as near-infrared...

The term half bandwidth (HBW) generally refers to the width of a spectral band or frequency range at half of its maximum...

A slight displacement in the position of a spectral line because of an alteration in frequency, as a result, in turn, of a...

Pertaining to electromagnetic radiation as perceived by the eye; that is, with the contributions as wavelengths in the...

Metasurfaces are two-dimensional arrays of subwavelength-scale artificial structures, often referred to as meta-atoms or...

A near-infrared (NIR) spectrometer is an analytical instrument used to measure the absorption, transmission, or reflection...

The Kerr effect, named after the physicist John Kerr who first observed it in 1875, is a nonlinear optical phenomenon where...

The recording and mathematical analysis of all spectral intervals of the spectrometer simultaneously.

A solid with a structure that exhibits a basically symmetrical and geometrical arrangement. A crystal may already possess...

The line from a spark or other very hot source that has greater intensity than that of a line produced by an arc or flame...

The ongoing expansion of the universe based on observations of the recession of distant galaxies from each other as...

A source that attempts to create the characteristics of an ideal blackbody. It consists of a cavity, generally spherical,...

The spectral transmission window in silica-based fibers between 830 and 850 nm.

The ratio of the intensities of two specified spectral lines of a source having vastly different excitation energies. This...

A type of electromodulation that measures changes in spectral reflectance.

A dichroic mirror, also known as a dichroic beamsplitter or interference filter beamsplitter, is an optical device that...

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic...

A narrow range of emitted or absorbed wavelengths.

In optical emission spectroscopy, the reduction in radiant power in the central portion of spectral lines arising from the...

A metal-semiconductor-metal (MSM) photodiode is a type of photodetector that consists of metal electrodes on a semiconductor...

A coating made up of many layers of material having alternating high and low refractive index. In this way, it is possible...

Any noise with a power spectral density that is the inverse of the signal's frequency and is therefore most significant for...

That term pertaining to the spectral region that can be perceived by the eye.

A color whose hue is not produced by a single wavelength in the visible spectrum, but is instead produced by mixing the...

A fiber optic spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to...

Plot of spectral luminous efficiency vs. wavelength.

A multidimensional array of values that is commonly used in programming to describe a time series of image data. Each...

A monochromator is an optical instrument used to isolate and select a narrow range of wavelengths from a broader spectrum of...

Reflectance spectroscopy is a technique used to analyze the reflective properties of materials across various wavelengths of...

A filter that controls the spectral composition of transmitted energy partially by the effects of interference. Frequently,...

Ratio of the radiant flux at a particular wavelength lm to that at any other wavelength l, such that both radiations produce...

An assembly of multiple prisms that disperses incident light into its spectral components without deviating light at the...

A type of modulation spectroscopy that measures spectral reflectance or transmittance changes induced by applying a...

An optical assembly refers to a collection of optical components that are carefully arranged and aligned to perform a...

The measurement of the intensity of spectral lines by the examination of a very small area under a microscope and the...

A classification of particular regularities that occur in the spectra of many atoms.

In atomic fluorescence spectroscopy, fluorescence emitted by an atom at a spectral line of a wavelength identical to that of...

The spreading of potentially equal radiation frequencies that results in broadening of the spectral line. This effect is...

Celestial point sources that emit specific wavelengths of radiation that appear on spectral charts as narrow lines. The term...

The wavelength at which a lamp radiates its highest intensity.

A filter exhibiting transparency, absorption or reflectance characteristics specifically for spectral control of wavelengths...

Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of...

The entrance slit, also known simply as the slit, is an essential component in optical instruments such as spectrometers and...

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel...

GaN (Gallium Nitride) distributed feedback (DFB) lasers refer to a specific type of semiconductor laser based on Gallium...

A temperature radiator whose spectral emissivity at all wavelengths is in constant ratio (less than unity) to that of a...

The term "Rydberg atom" refers to an atom in a highly excited state where one or more of its electrons are in a Rydberg...

Irradiance per unit wavelength interval at a given wavelength, expressed in watts per unit area per unit wavelength interval.

A mid-infrared camera is a type of imaging device designed to capture images in the mid-infrared (mid-IR) spectral range,...

A wavelength region of relatively high transmittance, surrounded by regions of low transmittance.

The use of narrow bandpass filters and special photographic emulsions to discern features of a surface that would not be...

A shift in the direction of the red in the spectral lines of light which, defined by the relativity theory, will have...

The Lorentz oscillator model is a theoretical model used in physics to describe the response of a charged particle (such as...

A perfect diffuser that exists only as a concept, or a white with known spectral characteristics used as a reference in...

An optical fiber in which ions of a rare-earth element, such as neodymium, erbium or holmium, have been incorporated into...

A fluorophore is a molecule or a portion of a molecule that has the ability to emit light upon excitation by an external...

Radiance per unit wavelength interval at a given wavelength, expressed in watts per steradian per unit area per wavelength...

Broadening of a laser's spectral linewidth when the resonance frequencies of the atoms (or molecules) of the medium are not...

Multispectral imaging is a technique that involves capturing and analyzing images at multiple discrete spectral bands within...

The splitting or shifting of spectral lines or energy levels caused by the application of a strong transverse electrical...

An optical testing instrument is a device or system used to evaluate and measure the performance, quality, and...

A laser using a dye solution as its active medium. Its output is a short pulse of broad spectral content and its achievable...

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples....

A filter used in photography to change the spectral composition of light entering a camera, or to adjust color balance...

When, for example, a beam of monochromatic light passes through a diffraction grating, the emergent rays that have remained...

A type of pyroelectric detector with favorable qualities of linearity, sensitivity and spectral responsivity used in FTIR...

A photovoltaic device that consists of multiple p-n junctions to produce a greater efficiency when in use than that of...

A light filter that equally decreases the intensity of all wavelengths of light without altering the relative spectral...

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties...

Source of radiation defined or specified by its spectral power distribution.

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists...

The ratio of radiant energy reflected from a rough surface to that incident on it. Usually, the radiant energy is total...

Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a...

The slight difference in wavelength of an element's given spectral line observed in comparing different isotopes of that...

Optoacoustic, or photoacoustic, refers to a phenomenon and related techniques that involve the generation of acoustic waves...

A sensitometer having a continuously controlled monochromator to measure spectral sensitivity and contrast of photographic...

Etaloning is an optical phenomenon that occurs in imaging systems, particularly in devices such as spectrometers,...

Visual equivalence of physically (usually spectrally) different stimuli.

1. A faint second image caused by reflection that is sometimes seen when observing through an optical instrument. 2. With...

Self-phase modulation (SPM) is a nonlinear optical phenomenon that occurs when an intense laser beam passes through a...

Two stars so close together that they cannot be resolved by telescopes. They are proved to be double stars by the doubling...

Also known as a gray body; a nonselective radiator is a thermal radiator that has a constant spectral emissivity with...

In colorimetry, the phenomenon in which spectrally different radiations produce the same color sensation for a given...

A prism or series of prisms used to disperse a beam of radiant energy of mixed wavelengths into its spectral components.

Average wavelength usually determined for light-transmitting devices by taking a weighted average for each wavelength of the...

In dry etching, a method of characterizing the composition of solid materials such as metal. Atoms in the OES technique are...

The detection and measurement of spectral reflectance, spectral transmittance or relative spectral emittance, relative to...

Spectral repeatability refers to the consistency and reproducibility of spectral measurements across multiple trials or...

The amount of energy required to raise the energy level of an atom; a necessity if the atom is to radiate energy. High...

A coating applied to a neutral density glass that is designed to reduce the amount of light evenly across the transmitted...

In an astigmatic grating, the image of the entrance slit located at the primary focus.

The random noise having a spectral density that is substantially independent of the frequency over a specified frequency...

Ratio of radiant flux weighted according to V(l), the spectral luminous efficiency, to the corresponding radiant flux.

In a crystalline substance, the spectral range of states of energy that contains the crystal's binding valence electrons.

The unchanging nature of spectral reflectance as vegetational density increases to the point where additional increases in...

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds,...

Optical coherence tomography (OCT) is a non-invasive imaging technique used in medical and scientific fields to capture...

The frequency domain is a concept used in signal processing and analysis to represent signals and data in terms of their...

A photomultiplier tube (PMT) is a highly sensitive vacuum tube that detects and amplifies low levels of light. It is widely...

The separate spectral lines formed by a diffraction grating that are characterized by one wavelength difference in path...

A transparent powdered solid immersed in a liquid or plastic of similar refractive index but widely different dispersion;...

The wavelength interval in which radiant intensity is at least 50 percent of the maximum spectral value.

Spatial resolution refers to the level of detail or granularity in an image or a spatial dataset. It is a measure of the...

Temperature of the blackbody having a spectral power distribution approximately proportional to the test source at all...

1. A thin parallel plate of material that transmits in the infrared region. See infrared optical material. 2. A spectral...

A blackbody source, often simply referred to as a blackbody, is a theoretical or practical physical object that absorbs all...

The formula that gives the wavelength of maximum spectral radiant emittance of a perfect blackbody: λmax =...

Broadband dielectric mirrors, also known as broadband mirrors, are optical coatings designed to efficiently reflect or...

The output of spectral channels written as an integral function of known solar irradiance, atmospheric transmittance and...

A photodetector, also known as a photosensor or photodiode, is a device that detects and converts light into an electrical...

Supercontinuum refers to a broad spectrum of light that spans a wide range of wavelengths, typically from the visible to the...

With respect to color photography, the measurement, at a given wavelength, of the way the color film modulates the radiant...

Gallium nitride (GaN) is a compound made up of gallium (Ga) and nitrogen (N). It is a wide-bandgap semiconductor material...

The frequency space between consecutive transmission peaks in the transmission spectrum of a Fabry-Perot interferometer or...

An instrument that spectrally analyzes the flux reflected from a material. The reflected flux may be total, diffuse or...

A frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with...

The formula describing the spectral radiant emittance of a perfect blackbody as a function of its temperature and the...

A nonlinear label-free imaging technique commonly used during surgical procedures for the visualization of collagen fibers...

A finite version of Shannon's sampling theorem that states that a class of functions can be reconstructed exactly by a...

A small handheld instrument consisting of a slit and collimator that feeds light into a small direct-vision dispersing...

Any pyrheliometer that has a filter placed over its sensor to limit the range of solar radiation it will detect; used to...

A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format....

A photoreceptor material used in solar cells and in drums for laser printers and high-speed copiers because of its high...

A measure of the wavelength extent of a spectrum.

Monolithic self-scanning linear image sensor array for multichannel spectroscopy with a spectral range of from 200 to 1000...

Laser-induced fluorescence (LIF) is a spectroscopic technique that involves using a laser to excite molecules or atoms,...

The graph of a curve describing the spectral irradiance of extraterrestrial sunlight.

An InGaAs (indium gallium arsenide) camera is a type of imaging device that utilizes InGaAs sensors to capture images in the...

FTIR (Fourier transform infrared) spectrometer is a powerful analytical instrument used to obtain an infrared spectrum of...

An emission spectrum is a graphical representation or a characteristic pattern of the wavelengths or frequencies of light...

An instrument used to record the emittance or reflectance of an object by scanning with discrete spectral resolution over a...

Rare earth dopants refer to elements from the lanthanide series, also known as rare earth elements, that are intentionally...

A method of spectral analysis using wavelengths between 100 and 300 nm that utilizes both emission and absorption techniques.

The fundamental tool of microdensitometry, the microdensitometer is an instrument used for the precise measurement of...

A mounting used for large concave gratings, whereby the slit, grating and plate holder lie in the Rowland circle, and the...

The slits in a spectrograph that form images of spectral lines. Slits may be bilateral or unilateral, and generally close...

The measured wavelength of the most distinct edge of a spectral band.

A diagram in which the variable frequencies of a spectral band system are plotted corresponding to ascending values of the...

Full width half maximum (FWHM) is a measure of the extent of a function. Given by the difference between the two extreme...

Photographing of terrain on the ground and objects in the air by cameras mounted in aircraft; utilized in satellites,...

Spectral domain optical coherence tomography is an imaging technique used in medical diagnostics, particularly in...

A spectral line of an internal standard; used to compare radiant energy of the line being analyzed.

An optical filter is a device that selectively transmits or blocks specific wavelengths, or colors, of light. Optical...

Also called complementary dominant wavelength. On a chromaticity diagram, the wavelength on the spectrum locus that lies on...

Characterizes the significant solar radiation at the surface of the earth, so named because its spectral range extends only...

An electric arc that is formed in mercury vapor through which an electric current flows. The intensity of the illumination...

Measure of a detector's signal during exposure to radiation of a constant power level and varying wavelength.

The relationship between different wavelengths of light generated by a source, which may affect the spectral distribution of...

A chart formed by a spectrograph; the record of the spectral range. See spectrograph.

The broadening of spectral lines due to the collision of radiating particles with one another and the resulting interruption...