Photonics Dictionary: F

The distance between the surface of a ferrule and the surface of a fiber end, provided that the ferrule extends above the fiber end. If the fiber end extends above the ferrule surface, the difference...

A microscope in which laser light is delivered through single-mode fibers that replace the pinhole usually used in confocal microscopy. When the Gaussian mode is imaged from the fiber output onto the...

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...

One or more spots placed in the field of view of an optical system to provide a means of reference.

1. In raster scan television, one of the two scans that are interlaced to make up a frame. 2. See field of view.

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 extremely powerful microscope that renders individual ionized atoms visible by using an electric field to propel the ions to a fluorescent screen where they are magnified.

1. A lens situated at or near the plane of an internal image to project the aperture of a previous objective or erector upon the aperture of a following lens. 2. A lens at or near the plane of a...

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...

The number of fields scanned per second in a television system. The US standard is 60. Also called field frequency.

A device used to scan images or information on photographic film for the subsequent relay of information.

The process by which the light from the images of photographic film is encoded into electrical signals for video transmission.

An interferometer spectrometer designed to measure thicknesses of thin films or layers by recording the interferogram and by having a computer within the instrument to establish the distance between...

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 device that holds a number of filters and allows the filter with the desired characteristics to be rotated into an optical aperture.

A low-power telescope with a wide field of view, typically attached to a higher power telescope with a narrower field of view. This enables an observer to locate a celestial object with the...

For a Fabry-Perot interferometer or etalon, a value for the transmission bandwidth which can be calculated as the ratio of the free spectral range to the full width half maximum of the transmission...

The process of grinding the concave surface of a single-vision spherical lens.

The process of grinding the toric surface of a single vision sphero-cylindrical lens.

Describes devices that are not provided with a means of focusing.

Fixed-pattern noise is the measure of the static (nontemporal) differences between pixels when the detector is evenly illuminated. In microbolometers, this effect is mostly caused by mismatch between...

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 device used to measure the speed of light by adjusting the rotation of a toothed wheel so that light passing through one tooth opening is reflected through the next. This device has since been...

A filter, partially opaque to near-ultraviolet, visible and infrared radiation, that may be made by exposing and processing photographic film. Such materials are almost equally opaque to radiation of...

A spectroscopic technique used in the detection of free radicals by virtue of their electronic spectra. In this method, an intense light flash is used to form extensive photolysis and yield a high...

A technique used in radiography to obtain an unblurred image of a moving object by the use of very short x-ray exposures, such as one microsecond, to record the image.

A device that is designed to automatically turn electric lamps on and off in a rapidly repeating sequence. The device may use a motor-driven mechanism or a combination heater filament and bimetallic...

A device that converts stored electrical energy into light by means of a sudden electrical discharge.

A pulsed dye laser in which the excitation is provided by means of a flashlamp. Output is tunable from 335 to 850 nm, with peak power up to 7000 kW.

A piece of glass having a crude plano surface on each side.

An electronic display in which a flat screen is formed by an orthogonal array of display devices, such as electroluminescent devices, light-emitting diodes or liquid crystal cells.

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.

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...

The fluctuation in apparent illumination that has a rate comparable to the reciprocal of the period of persistence in vision.

An instrument designed to give a visual indication to the pilot when the plane has strayed from a specific flight path.

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

An automatic camera that can record reduced images of documents at a rate of up to 30,000 documents per hour by having the film and documents move synchronously in opposite directions.

In various fields such as fluid dynamics, microfluidics, and biotechnology, a flow channel refers to a defined pathway through which a fluid (liquid or gas) flows. The channel can be of various...

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...

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...