Photonics Dictionary

The total range of wavelengths, extending from the shortest to the longest wavelength or conversely, that can be generated physically. This range of electromagnetic wavelengths extends practically...

An EMCCD (electron-multiplying charge-coupled device) camera is a type of scientific camera specifically designed for low-light imaging applications that require high sensitivity and fast readout...

An electron-beam tube with power-handling capability that is essentially based on controlled electron beams. Its control and screen grids are basically in alignment.

An electron-beam lithography (EBL) system is a sophisticated nanofabrication tool used in the semiconductor industry and research laboratories to pattern extremely fine features with sub-micrometer...

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

An emission spectrum is a graphical representation or a characteristic pattern of the wavelengths or frequencies of light emitted by a source, such as an atom, molecule, or celestial object. It shows...

The occurrence of very large rotations in transparent materials at weak magnetic fields as predicted in the classical dispersion theory. This effect was discovered by Mavaluso and Corbino in 1898 in...

Enhanced picture archiving and communication system (PACS) display (ePAD) is a software tool used in medical imaging to view, manipulate, and analyze radiological images, such as x-rays, CT scans,...

An enzyme-linked immunosorbent assay (ELISA) is a laboratory technique used to detect and measure the presence of specific substances, such as antibodies, antigens, proteins, hormones, or other...

When a block of glass (prism, window, filter, etc.) is placed into a converging light bundle, it increases the physical distance to the point of focus. The equivalent air path for that block of glass...

Excimer laser coronary angioplasty (ELCA) refers to a medical procedure used in the treatment of coronary artery disease. This technique involves the use of an excimer laser to perform angioplasty, a...

An exciton is a quasiparticle that represents the bound state of an electron and a hole in a solid-state material, typically a semiconductor or an insulator. In simpler terms, an exciton is a paired...

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds, where one femtosecond is equal to 10-15 seconds. These lasers are capable of...

A fiber Bragg grating (FBG) is a type of optical filter that is inscribed or "written" into the core of an optical fiber. It consists of a periodic modulation of the refractive index along the length...

A phenomenon in which high optical power, encountering an imperfection in an optical fiber, destroys the fiber's core and causes damage to back-propagate down the fiber. It is caused by classic...

A fiber laser is a type of laser in which the active gain medium is an optical fiber doped with rare-earth ions such as erbium, ytterbium, or neodymium. Fiber lasers generate coherent light through...

A fiber optic gyroscope (FOG) is a type of gyroscope that uses the interference of light waves to detect changes in orientation or rotation. It operates based on the principle of the Sagnac effect,...

A fiber optic sensor is a device that uses optical fibers to detect and measure physical, chemical, biological, or environmental parameters. Unlike traditional electrical sensors, fiber optic sensors...

A fiber optic transceiver, often simply referred to as an "optical transceiver," is a device used in fiber optic communications to transmit and receive data over optical fibers. It integrates both a...

A fiber-coupled LED (light-emitting diode) refers to an LED device that is optically coupled to an optical fiber for the purpose of efficient light transmission. In this configuration, the LED serves...

Fizeau fringes are interference fringes observed in an interferometer, specifically in a Fizeau interferometer. The Fizeau interferometer is named after the French physicist Armand Fizeau, who...

Flow cytometry is a powerful technique used in biology and medicine for the quantitative analysis of the physical and chemical characteristics of cells and particles suspended in a fluid. The method...

Fluence is a term used in various scientific and technical disciplines to describe the amount of something per unit area. The specific meaning of fluence can vary depending on the context in which it...

Fluorescence lifetime refers to the average time it takes for a fluorophore, a molecule that absorbs light at one wavelength and emits it at another, to return to its ground state after being excited...

Fluorescence microscopy is a specialized optical imaging technique used in biology, chemistry, and materials science to visualize and study specimens that exhibit fluorescence. Fluorescence is the...

A fluorophore is a molecule or a portion of a molecule that has the ability to emit light upon excitation by an external energy source, such as ultraviolet or visible light. The process by which a...

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

Free-space optics (FSO), also known as optical wireless communication or optical wireless networking, refers to the transmission of data using modulated beams of light through free space (air or a...

A frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with great accuracy. The term "frequency comb" is often associated with the Nobel...

A unit of frequency equivalent to 1012 cps. Named for Augustin Jean Fresnel, a French physicist known for his work in light and optics.

Fresnel reflection refers to the reflection of light at the interface between two different media with different refractive indices. This phenomenon was named after the French engineer and physicist...

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 materials refer to materials that possess specific properties or functionalities that make them suitable for particular applications or purposes. These materials are designed and...

Fused quartz and silica are closely related materials, both composed primarily of silicon dioxide (SiO2), but they are produced through different manufacturing processes and have distinct properties...

The physical center of the lens; it is on the axis of the lens, halfway between the front and rear vertex. It is sometimes referred to as the mechanical center of the lens.

The position and shape of the image of a point source, as predicted by geometric optics alone. The geometric image is to be differentiated from the diffraction image, which is determined from...

A field of physics that deals with light as if it truly were composed of rays diverging in various directions from the source and abruptly bent by refraction or turned by reflection into paths...

Germanium crystal refers to a crystalline form of the element germanium (Ge), which is a metalloid and semiconductor commonly used in various electronic and optical applications. Germanium crystals...

The Golgi staining technique (also called the black reaction) makes it possible to look at the nervous system by rendering neurons visible under light microscopy. After a long process involving...

Graphene is a two-dimensional allotrope of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice pattern. It is the basic building block of other carbon-based materials...

The process of subjecting glass to temperature cycling to produce physico-chemical reactions that alter its properties. Similar processes can be accomplished with a laser -- most commonly a CO2,...

A gas lamp used in the early 1900s as a physical standard for measurement of luminous intensity. The Hefner unit was superseded by the candle and then by the candela.

The holographic recording of a microscopic specimen whereby magnification is achieved by alteration in a wavelength or radius of curvature between recording and reconstruction of the wavefront. With...

The application of coherent wavefront techniques to the determination of the physical state of a system without appreciably altering that state.

Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional reconstructions of transparent or weakly scattering objects with high...