Photonics Dictionary

A tool used to determine the curvature of a lens surface in terms of dioptric power. See lens watch; spherometer.

3D profiling, also known as three-dimensional profiling, refers to the process of capturing, analyzing, and visualizing the three-dimensional shape, geometry, and surface characteristics of objects...

An abridged spectrophotometer refers to a simplified or compact version of a traditional spectrophotometer, which is a scientific instrument used to measure the intensity of light at different...

The absolute luminance threshold is the lowest luminance level of a light source or illuminated object that can be detected by the human eye under specific conditions. This threshold represents the...

An absorbing wedge is an optical device used to control the intensity of light passing through it by absorbing a portion of the light. It is typically used in experiments and optical systems where...

Absorptance refers to the fraction of incident electromagnetic radiation (such as light or infrared radiation) that is absorbed by a surface, rather than being reflected or transmitted. It is a...

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...

Absorption spectroscopy is a fundamental analytical technique used to study the interaction between electromagnetic radiation and matter. It involves measuring the absorption of light by a sample...

The measured change in absorption at a single wavelength while altering experimental parameters such as the incident intensity or pulse width.

Actinic radiation refers to electromagnetic radiation that has enough energy to induce photochemical reactions. This type of radiation is primarily in the ultraviolet (UV) range but can also include...

Actinism refers to the property of radiation, particularly light, that enables it to produce photochemical effects. This term is derived from the Greek word aktinos, meaning ray. Here are the key...

Radioactivity refers to the spontaneous emission of radiation from the nucleus of an unstable atom. This emission occurs as the nucleus undergoes radioactive decay, which is a natural and random...

Visual acuity specifically refers to the clarity or sharpness of vision, typically measured by the ability to discern the details of objects at a specific distance. It is a fundamental measure of the...

Acutance refers to the perceived sharpness of an image in terms of the contrast of edges, rather than the resolution of fine details. It relates to how well-defined and crisp edges appear in a...

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

Adiabatic laser colorimetry is a technique used to measure the color of materials based on the principle of adiabatic demagnetization. Principle: Adiabatic laser colorimetry relies on the...

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...

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...

A ball lens is a small, spherical optical component typically made of glass or other transparent materials. It is characterized by its spherical shape, with both its front and back surfaces forming...

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

In semiconductor physics, the term bandgap refers to the energy range in a material where no electronic states are allowed. It represents the energy difference between the valence band, which is the...

The distance between pupil centers in a two-pupil system, measured perpendicularly to the optic axis.

Beam profiling is a technique used to characterize and analyze the spatial intensity distribution of a laser beam. It involves measuring and visualizing how the optical power or intensity is...

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...

Bioluminescence is the natural phenomenon where living organisms produce light through a chemical reaction. In the context of photonics, bioluminescence has significant implications for both research...

A technique in which a beam of x-rays is directed against a crystal, the atoms of which, because of their lattice arrangement, reflect the ray in the same way as a series of plane surfaces. If the...

Brillouin microscopy is a non-invasive imaging technique that utilizes Brillouin scattering to measure the mechanical properties of materials at the microscale. This advanced optical technique...

Focal, nodal or principal points of a lens. If the respective distances of the object and image are measured from the cardinal points, all thin-lens equations are applicable to thick lenses.

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...

The lens thickness measured at the optical axis.

Centration is the precise alignment of the optical center of a lens or optical element with its mechanical center or the axis of the mounting assembly. It is crucial for ensuring that the optical...

Chemical sensing refers to the detection and measurement of specific chemical compounds or substances in various environments or samples. It involves the use of sensors or analytical techniques to...

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...

Cold atoms refer to atoms that have been cooled to extremely low temperatures, typically in the microkelvin (µK) to nanokelvin (nK) range, close to absolute zero (0 Kelvin or -273.15°C). At...

A laser warning and countermeasure system containing a sensor that indicates the direction of a laser beam, and analytical instruments to determine pulse code, repetition frequency and wavelength.

Computational imaging refers to the use of computational techniques, algorithms, and hardware to enhance or enable imaging capabilities beyond what traditional optical systems can achieve. It...

The ratio between the object distance and the image distance measured along the principal axis of a lens or mirror. An object at the focal point of a lens has an infinite conjugate ratio; an object...

A cryogenically cooled long-wave infrared (LWIR) camera is a specialized thermal imaging device designed to detect infrared radiation in the long-wave infrared spectrum, typically ranging from 8 to...

The measure of departure from a flat surface, as applied to lenses; the reciprocal of radius. Applies to any surface, including lenses, mirrors and image surfaces.

A technique for measuring fiber attenuation or distortion by performing two transmission measurements. One is at the output end of the full length of the fiber. The other is within 1 to 3 m of the...

A multidimensional array of values that is commonly used in programming to describe a time series of image data. Each dimension in the data cube represents a new attribute, while the cells of the...

A measure of the sensitivity of a detector; the reciprocal of noise equivalent power (NEP). See D*.

A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format. Each element within the array is capable of detecting electromagnetic...