Photonics Dictionary: F

A region far from an aperture or source where the diffraction pattern is essentially the same as that at infinity. Changes in diffraction patterns of points within the far-field region are...

A fiber optic imaging bundle is a specialized optical device composed of multiple optical fibers bundled together. Each fiber optic strand within the bundle acts as a conduit for transmitting light....

Fluorescence lifetime imaging (FLIM) is an advanced imaging technique that provides information about the lifetime of fluorescence emissions from fluorophores within a sample. Unlike traditional...

A multiple-beam interferometer, usually consisting of two flat plates, with high reflective ability. The plates are set parallel to one another by spacers so that lightwaves may bounce back and forth...

1. One of the plane-reflecting surfaces on a multisurfaced polygon. 2. The cleaved end mirror of a laser diode's active region.

In imaging technology, assigning color to black and white images to differentiate features or convey information. Also called colorizing.

A set of rays through a lens originating at a common point and contained in one plane.

The simultaneous collection of two or more signals at a single location. In a digital computer, it refers to the number of inputs that can be accommodated by a particular logic circuit.

The distribution of one signal to more than one location. In a digital computer, it refers to the number of outputs that can be fed by a particular logic circuit.

A grating with very coarse rulings to match the long wavelengths in the far-infrared region. In the most efficient ruling method, grooves are cut in plane, solid aluminum alloy blanks.

A laser with output over a wide range of wavelengths spanning the far-infrared region of the spectrum (30 to 1000 µm); typically, it consists of a metal or dielectric waveguide one to two...

A gas maser that is capable of producing radiation in the far-infrared region of the spectrum.

That radiation characterized by wavelengths ranging from 0.2 to 0.3 µm in the electromagnetic spectrum.

A type of mirage that creates a distorted vertical image of relatively flat objects so that they appear as mountains, cliffs, columns or castles. The nonexistent mountainous region in the Arctic...

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...

The mathematical expression of the probability of any given state of energy being occupied when a semiconductor is in thermal equilibrium.

The region of a ferroelectric crystal where spontaneous polarization is uniformly directed.

Ferroelectric materials are a type of dielectric materials that exhibit spontaneous electric polarization, meaning they possess a permanent electric dipole moment even in the absence of an external...

A mechanical fixture, generally a rigid tube, used to confine the stripped end of a fiber or a fiber bundle.

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 rigid or flexible, concentrated assembly of glass or plastic fibers used to transmit optical images or light. See aligned bundle; incoherent bundle.

A standard for fiber optic data transmission systems being developed by the American National Standards Institute (ANSI) and associated working groups that will make fiber optic components from...

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 cable assembly refers to a complete unit consisting of optical fibers, connectors, protective jackets, and other components that are assembled together to facilitate the transmission of...

A fiber optic preform is a cylindrical glass rod or tube used as the starting material for manufacturing optical fibers. It serves as the precursor from which optical fibers are drawn. The process of...

A coherent optical fiber bundle in which the configuration is flat rather than round, giving an output in a line.

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 spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to transmit light from a source to a spectrometer unit, where the light is...

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...

A photodetector employing photoregeneration of carriers in the channel region of an FET structure to provide photodetection with current gain.

An X-Y electrically addressable series of arrays with individual electron emitters bombarding a phosphor-coated transparent plate. The phosphor is induced into luminescence, similar to traditional...

An image-forming instrument in which a strong electrostatic field causes cold emission of electrons from a sharply rounded point or from an object that is located on that point. The electrons are...

An expression of the tolerance of decentration of a laser diode from the optical axis: the region around the axis in the focal plane of the collimator in which the facet can be located and still...

The field of view (FOV) refers to the extent of the observable world or the visible area that can be seen at any given moment through a device, such as an optical instrument, camera, or sensor. It is...

Intensity of emission as a function of direction in a given plane.

An aperture located at an image plane of an optical system that determines the size and shape of the image.

The allowable departure from the given figure or geometrical form. It may be described in terms of fringes or wavelengths.

In optics, the geometrical form of an optical surface.

Filoviruses are a family of viruses that are responsible for severe and often fatal hemorrhagic fevers in humans and non-human primates. The name "filovirus" is derived from their filamentous...

1. With respect to radiation, a device used to attenuate particular wavelengths or frequencies while passing others with relatively no change. 2. See digital filter.

A type of interferometer noted for producing narrow multiple-beam interference fringes. As a result, when compared with the Twyman-Green, the Fizeau interferometer has fewer optical components, does...

An imaging device analogous to a drum scanner, but operating at greater speeds; it uses a row of sensors to traverse an image affixed to a flat surface.