Photonics Dictionary

The properties exhibited by a semiconductor as the result of its modification by imperfections and impurities in the crystal.

The organ of vision or light sensitivity.

A shield of rubber, plastic or metal used to protect the eyes of the observer from stray light and wind, and to maintain the proper eye distance.

Also termed eye distance. The distance between the vertex of the last optical surface of a visual optical system and the system's exit pupil.

Wavelengths between 400 and 1400 nm (VIS to NIR) are focused onto the retina by the cornea. Because the retina is sensitive to light, these wavelengths can be damaging even at low energies. It is the...

Also known as ocular. The lens system used between the final real image in a visual optical system and eye. It acts as an image magnifier. Many types of eyepieces are known; e.g., the Huygens used in...

The expression denoting the ratio of the equivalent focal length of a lens to the diameter of its entrance pupil.

An f-theta lens, also known as an f-theta scan lens or simply an f-theta lens system, is a specialized optical component used in laser scanning systems, particularly in laser marking, engraving, and...

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

The series of rings when monochromatic light passes through a Fabry-Perot interferometer.

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.

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...

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.

The spectroscopic analysis of interference patterns using a monochannel spectrometer, spectrograph or multichannel spectrometer with a Fabry-Perot interferometer to record the fringes.

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...

The degradation of the facets in a laser diode due to the intensity of radiation.

Data gathered by a facsimile system and converted into graphic, readable form; generally used in meteorology. Also known as fax chart or fax map.

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.

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.

Measurement of the interval during which a photodetector's signal and output current drops from 90 to 10 percent.

A secondary halo whose movement counterpoints the behavior of the Becke line.

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.

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

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 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.

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.

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

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.

The nonluminous area that divides the negative glow from the positive column in a Crookes tube under conditions of moderate pressure.

The Faraday effect, named after the English scientist Michael Faraday, is a phenomenon in physics where the polarization plane of light is rotated when the light passes through a transparent medium...

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...

A FAC lens, or fast axis collimation lens, is an optical component used in laser diode systems to collimate the fast axis of laser emission. Laser diodes emit light in two main axes: the fast axis,...

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...

The decrease of a component's efficiency, or a reduction in a material's light sensitivity, as the result of accumulated exposures to radiant energy.

The fiber optic connector standard for Nippon Telephone & Telegraph (NTT) installations, developed with Nippon Electric Co. (NEC).

In image processing and machine vision, the process in which an initial measurement pattern or some subsequence of measurement patterns is transformed to a new pattern feature. In image pattern...

The placement of a device or an additional circuit into a feedback control system to improve its response in relation to a specific characteristic of the system.

A waveguide or coaxial cable that transmits a signal from an antenna to a receiver or from a transmitter to an antenna.