Photonics Dictionary: F

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.

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...

A method used to produce precision spherical and aspheric molded glass lenses without grinding or polishing.

A type of wide-angle lens that has an angular field above 140° and that exhibits barrel distortion. The most commonly used fish-eye lenses have a field of about 180°, though they are...

A lens that focuses on a flat plane because its field of curvature is close to zero.

A lens having an extremely high aperture and used in the recording of x-ray fluorescent screen images. It often is specially designed for the camera, the color of the light and the image...

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

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...

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...

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

The object distance at which the eye is focused with the eye lens in a neutral or relaxed state.

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...

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

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...

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 property of optical fiber that results from thermal stresses during manufacturing and is defined as the amount of curvature over any specified length of fiber.

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 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 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 scanner in which a fiber optic assembly replaces a lens system.

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 coherent fiber optic bundle made from fibers whose diameter changes gradually along its length. Used to magnify or reduce the input image.

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...

An optical instrument consisting of an objective lens, a coherent (usually flexible) fiber bundle and an eyepiece to examine the output of the fiber bundle.

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

The site behind the lens system in a camera where photographic media are positioned for exposure.

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 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.

The principal point of a lens relative to the object space.

The separate spectral lines formed by a diffraction grating that are characterized by one wavelength difference in path length between adjacent slits.

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.

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...