Photonics Dictionary: F

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 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 grating used as a reflectance filter, particularly in the far-infrared. Small plane gratings, blazed for the wavelength of the unwanted radiation, are produced for this purpose.

A reticle whose image may be moved about in a field of view.

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...

The restricting aperture located at the front of the lens. It is usually defined as the maximum diameter of the entrance cone at the front vertex, for the specified field of view at infinity focus.

Flow chemistry, also known as continuous-flow chemistry, is a chemical manufacturing process where reactions take place in a continuous stream of fluids (liquids or gases) rather than in batch...

FMCW lidar stands for frequency-modulated continuous wave lidar. It is a type of lidar (light detection and ranging) technology used for remote sensing, distance measurement, and 3D mapping. FMCW...

A nonabsorbing, multireflecting device, similar in design to the Fabry-Perot interferometer, that serves as a multilayer, narrow-bandpass filter.

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.

The maintenance of the same scanning relationship between the transmitting scanning spot and receiving scanning spot for each scanning line transmitted in a facsimile system.

The reproduction of a picture or image, produced by scanning the image and converting it into electrical signals that carry the image to be reproduced. Also known as fax.

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

The diffraction pattern of a source such as a light-emitting diode, injection laser diode or the output end of an optical waveguide observed at an infinite distance from the source.

Describes incident radiation propagating parallel to an externally applied magnetic field in magneto-optical experimentation.

The prefix denoting 10-15. (f).

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...

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...

The law stating that the critical fusion frequency is approximately proportional to the logarithm of the luminance and the area.

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...

Fiber joints, also known as fiber optic splices, refer to the connection points where two optical fibers are permanently joined together to form a continuous optical transmission path. These joints...

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 device used to prepare optical fiber end faces; a scribe line made by the cleaver's blade propagates across the fiber, resulting in a clean break.

A plate consisting of fused optical fibers with both surfaces ground and polished, and having the entrance surface curved to match the image curvature of the input lens system. The plate transmits to...

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 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....

A bundle of optical fibers arranged randomly for the purpose of transmitting energy, not an image.

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 device used for coding messages and having a fiber bundle that is aligned at both ends and scrambled in the middle, potted and cut. The resulting halves of the bundles serve as encoders or decoders...

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 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...

The face of a cathode-ray tube (CRT) that has a fiber optic sheet attached to its surface. The sheet's fibers are at right angles to the face, allowing the transmittance of the fluorescent trace...

The use of thin flexible glass or plastic fibers as wave guides — or "light pipes" — to channel light from one location to another. Fiber optics is based off of the principle of total...

An optical recording technique that uses light source(s), a beamsplitting cube, light detector(s) and an optical fiber chronically implanted in animal brain to deliver excitation light to neurons...

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...

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 method of terminating optical fibers by forming a lens directly on the end of the fiber, eliminating the need for precise end-to-end placement or epoxy sealing in fiber connections.