Photonics Dictionary

An optical lens manufactured to control the transmission of light over a specified wavelength range. Low absorption lenses are produced which are anti-reflection coated for UV, VIS and IR wavelengths...

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 achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

Cemented prisms of differing refractive indices which refract incident light and, due to differing refractive indices, will not spatially separate individual wavelengths.

Light diffracted by a solid (usually quartz in crystal or fused form) traversed by acoustic waves. If the ultrasonic wavelength is larger than the diameter of the light beam, the diffraction orders...

Any fluorescence in which the wavelength of the emitted light differs from that of the absorbed light.

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...

Dispersion that occurs when the medium's index of refraction decreases as the frequency of the propagating light increases. For a given medium, some wavelength ranges may produce anomalous dispersion...

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

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...

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...

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...

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...

Autofluorescence refers to the natural emission of fluorescence exhibited by certain biological structures or molecules when exposed to light. Unlike fluorescence that results from the application of...

A beamsplitter is an optical device used to divide a beam of light into two or more separate beams, typically by reflecting a portion of the incident light while transmitting the remainder....

The angular width of a radiation beam. With respect to a conical beam of light, it is the vertex angle of the cone. The beamwidth is a measure of the rate of divergence or convergence of a light...

A piece of glass polished flat on one side, with a pair of polished faces that form an angle close to 180° on the other side, the dividing edge running down the middle of the plate. It is used...

A filter that transmits light in a series of sharp, widely spaced wavelength bands by its sandwich construction of alternating layers of polarizing films and plates cut from birefringent crystal.

Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of a series of closely spaced parallel grooves or slits. The blaze height is...

The light wavelength for which the direction of reflectance from the groove face is identical to the angle of diffraction for a specified angle of incidence.

A blue diode laser is a type of semiconductor laser that emits light in the blue wavelength range of the electromagnetic spectrum, typically between 400 and 500 nanometers. Diode lasers are compact,...

Broadband dielectric mirrors, also known as broadband mirrors, are optical coatings designed to efficiently reflect or transmit light over a broad range of wavelengths. These mirrors are constructed...

The production of visible light by infrared radiation whereby the light is produced by heat and not by any direct change in wavelength; the transformation is indirect.

Cathode radiant sensitivity refers to the ability of a photocathode to convert incident radiant energy, typically in the form of light, into an electrical signal. Photocathodes are components used in...

Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a lens or optical system, leading to a failure to focus all colors to the same...

Circular dichroism (CD) is a spectroscopic technique used to study the structural characteristics of chiral (asymmetric) molecules, particularly biomolecules like proteins, nucleic acids, and certain...

A color center, in the context of materials science and condensed matter physics, refers to a specific type of crystallographic defect in a crystalline structure that introduces color to the...

The detection and analysis of the relative response of a material to light over the range of wavelengths.

Deep multiphoton microscopy is an advanced imaging technique used in biological and biomedical research to visualize structures and processes deep within tissues with high resolution. It combines the...

Deep ultraviolet (DUV or deep-UV) refers to a specific range of ultraviolet light with shorter wavelengths than those in the UV-A and UV-B regions. The exact wavelength range considered as DUV can...

A CCD device for sensing longer wavelengths, such as NIR and IR, that has a deeper depletion region than would be necessary for sensing in the visible wavelength range. Because the depth of charge...

Dense wavelength division multiplexing (DWDM) is an optical communication technique used to increase the data-carrying capacity of optical fiber networks by simultaneously transmitting multiple...

A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively transmit or reflect certain wavelengths of light while simultaneously absorbing...

A dichroic mirror, also known as a dichroic beamsplitter or interference filter beamsplitter, is an optical device that selectively reflects or transmits light based on its wavelength. Dichroic...

A lidar (light detection and ranging) technique used in pollution monitoring. Two light beams are emitted simultaneously, one at a wavelength that will be absorbed by the target particles, and the...

Diffraction efficiency is a measure of how effectively a diffractive optical element (DOE) or diffraction grating directs light into specific diffraction orders or achieves a desired optical effect....

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...

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 diode laser is a type of laser that uses a semiconductor diode as the active medium to generate coherent light. Semiconductor diodes are electronic devices that conduct electricity primarily in one...

A diode-pumped solid-state laser (DPSSL) is a type of laser system that uses semiconductor diode lasers to pump energy into a solid gain medium, resulting in the generation of coherent light. This...

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...

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

Dispersion refers to the phenomenon where different wavelengths (colors) of light travel at different speeds when passing through a medium. This variation in the speed of light for different colors...