Photonics Dictionary

A fiber-coupled photoconductive antenna (FCPA) is a type of optoelectronic device that combines a photoconductive antenna with optical fibers for the purpose of generating or detecting terahertz...

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...

A flexible display refers to a type of electronic visual display that is designed to be bendable, foldable, or rollable, allowing for unconventional form factors and enhanced portability. Unlike...

Fluorescence is a type of luminescence, which is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Specifically, fluorescence involves the absorption of...

Fluorescence and phosphorescence spectroscopy are techniques used to study the emission of light (photons) by molecules following their excitation by external energy sources. While both processes...

Fluorescence correlation spectroscopy (FCS) is a powerful analytical technique used to study the dynamics and interactions of fluorescently labeled molecules in solution at the single-molecule level....

Fluorescent proteins are proteins that exhibit the property of fluorescence, which is the ability to absorb light at a specific wavelength and emit light at a longer wavelength. These proteins are...

A fluorescent screen refers to a phosphorescent or fluorescent-coated surface that emits visible light when exposed to other forms of electromagnetic radiation, such as x-rays or ultraviolet light....

A method of synthesis for crystals such as KTP. The process involves the use of a high-temperature solution called flux to enable crystal growth. Flux dissolves the elements of the desired crystal,...

A rotating mirror coupled with a distant mirror and used in a system by Foucault to compute the velocity of light. Light moving from the rotating mirror to the distant mirror and back was following...

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...

Freeform mirrors refer to reflective optical components that deviate from traditional symmetric or rotationally symmetric shapes, such as spheres or paraboloids. Unlike conventional mirrors, which...

The frequency domain is a concept used in signal processing and analysis to represent signals and data in terms of their frequency components. In contrast to the time domain, where signals are...

Two plane mirrors that are not wholly located in the same plane. When light from a point source or slit reflects from the two mirrors, interference bands are revealed in the region where the light...

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...

Molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube. Also called buckyballs. Cylindrical fullerenes are called carbon nanotubes or buckytubes.

Fusion ignition refers to the point in a controlled nuclear fusion reaction where the energy released by the fusion reactions becomes self-sustaining, leading to a continuous release of energy...

Gallium arsenide phosphide (GaAsP) is a semiconductor alloy composed of gallium (Ga), arsenic (As), and phosphorus (P). It is commonly used in the fabrication of optoelectronic devices, particularly...

Gallium arsenide (GaAs) is a compound semiconductor material composed of gallium (Ga) and arsenic (As). It belongs to the III-V group of semiconductors and has a zincblende crystal structure. GaAs is...

A galvanometric scanner, also known as a galvanometer scanner or galvo scanner, is a type of optical scanning device used to rapidly and precisely direct a laser beam or other light source to...

Gallium nitride-based light-emitting diodes (GaN-based LEDs) are semiconductor devices that emit light when an electric current passes through them. These LEDs are constructed using gallium nitride...

A gas laser wherein the gas mixture is not exhausted into the atmosphere but is continually recycled. It is excited in the active region, cooled and re-excited. The GTL requires no constant gas...

A beam of light whose electrical field amplitude distribution is Gaussian. When such a beam is circular in cross section, the amplitude is E(r) = E(0) exp [-(r/w)2], where r is the distance from beam...

1. That branch of optics that illustrates the theory in which q is substituted for sin q in Snell's law. Effective results are achieved if the aperture and field angle are made very small. The...

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...

A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or phosphoric oxides. Common window or bottle glass is a mixture of soda,...

The substrate upon which a diffraction grating will be ruled. It must be dimensionally stable, and the surface must be polished to an accurate flat or spherical form as required by the grating. The...

In an optical waveguide, a mode whose field decays monotonically in the transverse direction everywhere external to the core and which does not lose power to radiation. Also called bound mode.

A halogen lamp, also known as a tungsten halogen, quartz-halogen, or quartz iodine lamp, is an incandescent lamp that uses a tungsten filament surrounded by a small amount of halogen gas, such as...

A head-up display (HUD) is a transparent display technology that presents information directly in the field of view of a user, typically without requiring the user to look away from their usual...

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

A compact optical projection system, mounted on or built into a helmet, and used to project data or a scene directly into the eyes of the wearer. Also called visually coupled display.

A heterojunction is a junction formed between two different semiconductor materials with differing band gaps. These materials can be of the same or different types (e.g., both n-type, both p-type, or...

A high-sensitivity camera is a type of camera designed to perform well in low light conditions, capturing clear and detailed images with minimal noise. These cameras typically feature advanced sensor...

A high-speed motion camera, also known as a high-speed camera or slow-motion camera, is a specialized imaging device designed to capture fast-moving events or phenomena at extremely high frame rates....

Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs at the cellular and subcellular levels. It is a field that focuses on the...

Holography is a technique used to capture and reconstruct three-dimensional images using the principles of interference and diffraction of light. Unlike conventional photography, which records only...

Homogeneous light refers to light that is uniform in intensity and color across a given area or space. In other words, homogeneous light sources produce illumination that is consistent and evenly...

A hydrogel is a three-dimensional network of polymer chains that are hydrophilic, meaning they have a strong affinity for water. This network structure allows hydrogels to absorb and retain large...

Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the electromagnetic spectrum. Unlike traditional imaging systems that record only a few...

A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide range of wavelengths within the electromagnetic spectrum, typically from...

Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a hyperspectral imaging system. In hyperspectral imaging, the electromagnetic spectrum is...

In optics, an image is the reconstruction of light rays from a source or object when light from that source or object is passed through a system of optics and onto an image forming plane. Light rays...

An image intensifier, also known as an image intensification tube or image intensification device, is a specialized electronic device used to amplify low-light-level images to make them visible to...

Immunohistochemistry (IHC) is a method for detecting antigens or haptens in cells of a tissue section by using labeled antibodies to bind specifically to their antigens. IHC is used for disease...