Photonics Dictionary

A featherlike flaw in a body of glass.

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 differential luminance threshold divided by the luminance.

To supply a signal to some point.

The transfer of a part of a device's or circuit's output back to its input.

An amplifying device that returns a portion of its output to its input as a means of modifying the device's performance.

A circuit that permits feedback in an electronic device.

A system designed to control the output quantity of a device by returning a portion of its output signal to its input. This results in the manipulation of the input quantity so that the desired...

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

The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds the SNR of a scanning spectrometer in the same time by a factor proportional...

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...

In microscopy, the measured distance between theoretical parallel lines that are drawn tangent to the particle profile and perpendicular to the ocular scale.

The principle that a light ray extending from one point to another will, after any number of reflections and refractions, follow the path requiring the least transit time. This is also known as the...

The Fermi liquid state refers to a specific state of matter in quantum mechanics, particularly describing the behavior of interacting fermions (particles with half-integer spin, such as electrons) at...

The mathematical expression of the probability of any given state of energy being occupied when a semiconductor is in thermal equilibrium.

A crystal capable of being polarized in the reverse direction when an electric field is applied.

The region of a ferroelectric crystal where spontaneous polarization is uniformly directed.

Film in which electric polarization is reversible when influenced by an electric field.

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 phenomenon whereby certain crystals exhibit spontaneous electric polarization. It is analogous with ferromagnetism.

The properties of certain materials that cause them to have relative permeabilities that exceed unity. This permeability permits the materials to exhibit hysteresis.

A mechanical fixture, generally a rigid tube, used to confine the stripped end of a fiber or a fiber bundle.

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

A prism with curved faces that collimates, reflects and refracts incident light. Often used in the production of spectrographs.

The mechanical centerline through the core of an optical fiber.

The lowest frequency at which the magnitude of the fiber transfer function decreases to a specified fraction of the zero frequency value. Often, the specified value is one-half the optical power at...

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 rigid or flexible, concentrated assembly of glass or plastic fibers used to transmit optical images or light. See aligned bundle; incoherent bundle.

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 standard for fiber optic data transmission systems being developed by the American National Standards Institute (ANSI) and associated working groups that will make fiber optic components from...

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...