Photonics Dictionary

The ratio of the radiant power transmitted by an object to the incident radiant power.

The central wavelength range of a transmitter based on the worst-case scenarios of temperature, manufacturing and other variations.

In fiber optic communications, a light source whose beam can be modulated and sent along an optical fiber, and the electronics that support it.

The ratio of diffusely transmitted flux to incident flux.

A hologram having an object wave that has been transmitted through the transparent object media to a mirror, reflected again and recorded on a medium.

A filter that allows heat radiation from an incident beam to pass without absorption or reflection.

The ratio of the radiant power transmitted to the second surface of a medium to the corresponding radiant power that has just passed through the first surface. Internal transmittance does not denote...

The greatest luminous transmittance possible for a specified chromaticity.

The part of incident flux that is transmitted with no scattering.

An electronic device used to encode video and audio signals of a television camera into radio waves that are broadcast to remote receivers. The video and audio components are transmitted...

With respect to microscopy, light that is directed through the specimen by a substage condenser.

An instrument that uses optical filtration in order to measure the transmittance for a discrete range or specific number of wavelengths.

A measuring device that uses a light-sensitive cell or detector to determine the amount of light transmitted by a substance.

Measures the absorption or sample transmittance over a range of specified wavelengths. Sample may be placed within the device and the transmission measured to an accuracy of given percent. The...

A curve expressing an optical fiber's total transmitted power as a function of its launch angle at the input.

A bulk crystalline optic which permits the propagation of light through a volume of index altered material. The variation in refractive index along the material volume is due to a piezoelectric...

The change in refractive index that occurs as acoustic vibrations are transmitted through an optical material.The index changes are periodic in relation to the frequency, spatial orientation, and...

A thermoplastic or optically transmitting hard plastic produced by applying polymerization initiator and heat to a monomer.

Glass designed to absorb most infrared and ultraviolet radiation while transmitting most of the visible region.

An aerial reconnaissance system that can transmit, in near real time, image data recorded by IR and visual-spectrum sensors, providing day, night and foul-weather intelligence.

Broadband radiation emitted by a laser that does not transmit through the optical element. It can be removed by filtering.

A type of fiber optic sensor that detects alteration in position, distance, pressure, liquid level or temperature by transmitting light across a gap to a reflector; a change in the light returned to...

A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for...

The second adjustable iris diaphragm in an optical system. In the common microscope condenser system, it usually is located beneath the substage condenser on a transmitted light microscope. When the...

The formation of an image by a pinhole aperture that transmits radiation, such as gamma radiation.

A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or...

A range of wavelengths within which radiation transmitted through the atmosphere suffers relatively little absorption by atmospheric gases.

An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

The analysis of the atomic structure of a sample by means of a source radiation that is absorbed and emitted by the sample with lines corresponding to the number and arrangement of atoms. Generally a...

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples. It is particularly useful for analyzing solid and liquid samples without...

A receiver for optical communications systems consisting of a symmetric binary, pulse-code-modulated transmitter, a log-normal channel and an array of independent photocounting detectors that yield...

Refers to a display or screen that is illuminated from behind; the light is transmitted as opposed to reflected.

A filter that suppresses a given range of frequencies, transmitting only those above and below that band. Also called bandstop filter.

A relatively hard crystal, highly resistant to excessive energy radiation, that is frequently used for optical windows, prisms and lenses transmitting from the vacuum UV into the IR.

The simplest method of transmission on a local area network. The entire bandwidth of the cable is used to transmit a single unmodulated digital signal. Baseband transmission is capable of...

Transmittance of a stable solution is an exponential function of the concentration of the absorbing solute.

A branched fiber optic lightguide that performs both receiving and transmitting functions.

A filter that transmits light in a series of sharp, widely spaced wavelength bands by its sandwich construction of alternating layers of polarizing films and plates cut from birefringent crystal.

The ratio of the number of bits received incorrectly to the total number of bits transmitted digitally in a system.

A blackbody source, often simply referred to as a blackbody, is a theoretical or practical physical object that absorbs all electromagnetic radiation incident upon it and emits radiation in a...

A ground-based navigation beacon that emits pulsed signals which are picked up by aircraft making an instrument (blind) approach in landing. The signal is transmitted to the aircraft's L-scan...

A parallel plate of glass in such a position that the refracted and reflected rays of incident parallel light are mutually perpendicular. In this situation the reflected light is plane polarized, and...

Broadband dielectric mirrors, also known as broadband mirrors, are optical coatings designed to efficiently reflect or transmit light over a broad range of wavelengths. These mirrors are constructed...

A calcium indicator is a molecule that is sensitive to changes in calcium ion (Ca2+) concentrations in biological systems. These indicators are commonly used in various fields, including cell...

An optical wedge in which transmittance or density is a function of the location of the wedge, relative to a specific optical system.

The term sometimes used to describe the sequential arrangement of components in a video system -- from transmitter to receiver.