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Photonics Dictionary: F

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f
focal length; femto-
F
Farad; Fahrenheit
F-center -> color center
A color center, in the context of materials science and condensed matter physics, refers to a specific type of crystallographic defect in a crystalline structure that introduces color to the...
FAB
fast atom beam
Fabry-Perot cavity
An optical resonator in which feedback is accomplished by two parallel planes. In diode lasers, the planes are obtained by cleaving, polishing, etching, etc.
Fabry-Perot etalon
A nonabsorbing, multireflecting device, similar in design to the Fabry-Perot interferometer, that serves as a multilayer, narrow-bandpass filter.
Fabry-Perot fringes
The series of rings when monochromatic light passes through a Fabry-Perot interferometer.
Fabry-Perot interferometer
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...
Fabry-Perot laser
A laser oscillator in which two mirrors are separated by an amplifying medium with an inverted population, making a Fabry-Perot cavity. Standard diode lasers are Fabry-Perot lasers.
Fabry-Perot method
A means of determining a prism's index of refraction by placing the prism so that its emergent face is perpendicular to the incident beam. This arrangement permits the determination of the prism's...
Fabry-Perot mirror
A highly reflective mirror that is usually flat on one surface and curved on the other, and that has silver, gold or aluminum deposited on glass, providing about 99 percent reflection.
Fabry-Perot spectroscopy
The spectroscopic analysis of interference patterns using a monochannel spectrometer, spectrograph or multichannel spectrometer with a Fabry-Perot interferometer to record the fringes.
face-centered
With respect to a unit cell in a crystal structure, the property defining an atom located at the center of each face.
face-pumped laser
A device in which slab geometry internally compensates for thermal-optic distortion; the solid host material -- glass or Nd:YAG -- is in the form of a rectangular slab with plane parallel faces. The...
faceplate -> fiber optic faceplate
A plate made up of thousands of glass fibers arranged parallel to one another, i.e., in a coherent bundle, and fused together so that it is hermetically tight. It transfers an image from one plane to...
facet
1. One of the plane-reflecting surfaces on a multisurfaced polygon. 2. The cleaved end mirror of a laser diode's active region.
facet erosion
The degradation of the facets in a laser diode due to the intensity of radiation.
facsimile chart
Data gathered by a facsimile system and converted into graphic, readable form; generally used in meteorology. Also known as fax chart or fax map.
facsimile machine
A device used to transmit and receive images that have been converted to electrical signals over regular telephone lines; it includes a scanner, a transmitter, a receiver and a printer.
facsimile radio
The conversion of a still picture into sound waves and its subsequent transmission by radio.
facsimile synchronizing
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.
facsimile
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.
fall time
Measurement of the interval during which a photodetector's signal and output current drops from 90 to 10 percent.
false Becke line
A secondary halo whose movement counterpoints the behavior of the Becke line.
false color
In imaging technology, assigning color to black and white images to differentiate features or convey information. Also called colorizing.
false color process
Entirely analogous to color photography, but inclusive of light bands that do not appear in the visible spectrum.
fan
A set of rays through a lens originating at a common point and contained in one plane.
fan-in
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.
fan-out
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.
FAP
calcium fluorophosphate
FAR
Federal Acquisition Regulation; false alarm rate
far point (of vision)
The object distance at which the eye is focused with the eye lens in a neutral or relaxed state.
far-field diffraction pattern
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.
far-field region
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...
far-infrared grating
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.
far-infrared laser
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...
far-infrared maser
A gas maser that is capable of producing radiation in the far-infrared region of the spectrum.
far-infrared
That part of the infrared spectrum from about 30 to 1000 µm.
far-ultraviolet radiation
That radiation characterized by wavelengths ranging from 0.2 to 0.3 µm in the electromagnetic spectrum.
farad
The capacitance of a capacitor which has a potential difference of one volt between its plates when it is charged by one coulomb of electricity.
Faraday configuration
Describes incident radiation propagating parallel to an externally applied magnetic field in magneto-optical experimentation.
Faraday constant
The product of Avogadro's constant and the electrical charge of an electron; thus, the electrical charge carried by 1 gmol of a substance, or approximately 9.65 x 104 C.
Faraday dark space
The nonluminous area that divides the negative glow from the positive column in a Crookes tube under conditions of moderate pressure.
Faraday rotation
The effect discovered by Faraday in 1845 whereby nonoptically active materials or substances become capable of rotating the polarization plane of polarized radiation (light) passed through them when...
farbe -> color center
A color center, in the context of materials science and condensed matter physics, refers to a specific type of crystallographic defect in a crystalline structure that introduces color to the...
Farnsworth-Munsell test -> color perception test equipment
Equipment for testing an observer's color vision. Some tests require the identification or ordering of colored samples. The commercially available examples include: the Ishihara plates, on which...
FASE
fast advanced spin echo
fast axis
In a birefringent material, the index of refraction varies with the direction of vibration of a lightwave. That direction having a low refractive index is the fast axis; at right angles to it is the...
fast Fourier transform -> Fourier transform
Any of the various methods of decomposing a signal into a set of coefficients of orthogonal waveforms (trigonometric functions).
FASTAR
frequency angle scanning, tracking and ranging

Photonics DictionaryF

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