Photonics Dictionary

The emission of free electrons by a rise in temperature of the cathode alone.

A solid-state semiconducting structure (basically one of the bolometers) that changes electrical resistance with temperature. Materially, some kind of ceramic composition is used. A thermistor has...

A device composed of dissimilar metals that, when welded together, develop a small voltage dependent upon the relative temperature between the hotter and colder junctions. Banks of thermocouples...

Also known as analog thermogram. The resultant photograph, illustrating, in tones ranging from black to white, the spatial relationship of the infrared radiation temperatures of the different details...

Thermography is a technique that involves the use of an infrared imaging device, called a thermal camera or infrared camera, to detect and visualize the infrared radiation emitted by objects. This...

The production of an image on a magnetic film that is exposed to infrared radiation and heated to a point above Curie temperature in regions of the image. The image is contacted with paramagnetic...

Thermophotovoltaic (TPV) refers to a technology that converts heat energy into electricity using the principles of thermophotovoltaics. In a thermophotovoltaic system, thermal radiation from a heat...

An adhesive whose viscosity decreases as the temperature is increased to a limit. Canada balsam, resin and pitch are examples of thermoplastic cements.

An adhesive that permanently sets or hardens at a specified high temperature. Methacrylate is an example of a thermosetting cement.

Thin-film deposition equipment refers to machinery and tools used in the process of depositing thin layers of material onto a substrate surface. This technique is commonly employed in various...

Thomson scattering is a phenomenon in physics where electromagnetic radiation, such as light, is scattered by charged particles. It is named after the British physicist J.J. Thomson, who first...

1. In visual perception, the minimum value of stimulus that can be perceived on the average. 2. In optical detection systems, that signal level at which the probability of detection is 50 percent.

The minimum driving current corresponding to lasing threshold at a specified temperature. (Ith).

The time domain is a concept used in signal processing and analysis to describe signals in terms of their behavior over time. In the time domain, signals are represented as functions of time, showing...

(TOF) The length of time needed for a signal to arrive at and be reflected from the target. The basis of an active autoranging/autofocus system.

Time-correlated single photon counting (TCSPC) is a technique used in photon counting applications, particularly in the field of experimental physics, biophysics, and fluorescence lifetime imaging...

Time-lapse optical coherence tomography (OCT) refers to a medical imaging technique that captures a series of sequential OCT scans over time, allowing for the dynamic observation and monitoring of...

A time-to-amplitude converter (TAC) is an electronic circuit that converts a time interval between two events into an amplitude or voltage signal. TACs are commonly used in various scientific and...

A Ti:sapphire laser is a type of solid-state laser that utilizes a titanium-doped sapphire crystal as the gain medium. The name Ti:sapphire comes from the combination of titanium (Ti) as the dopant...

Topological photonics is a branch of physics and optics that explores the application of topological concepts to the behavior of light in photonic systems. Drawing inspiration from the field of...

Total internal reflection fluorescence (TIRF) microscopy is an advanced fluorescence microscopy technique that leverages the principle of total internal reflection to selectively illuminate and image...

1. The process of following an object's movement; accomplished by focusing a radar beam on the reticle of an optical system on the object and plotting its bearing and distance at specific intervals....

An instrument or system capable of both transmitting and receiving a signal.

A transducer is a device or component that converts one form of energy into another. It is commonly used in various fields, including electronics, acoustics, and instrumentation, to facilitate the...

A method of measuring total hemispherical emissivity of the plane surface of a solid that consists of thermally isolating a specimen of the material inside a vacuum, preheating it slightly above the...

The process whereby a quantum mechanical system alters from one energy level to another. During this process, energy is emitted or absorbed, and it usually takes the form of photons, phonons, or...

The decrease in power that occurs when an optical beam or signal is transmitted through a system.

In optics, the conduction of radiant energy through a medium. Often denotes the percentage of energy passing through an element or system relative to the amount that entered. See transmission...

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

A computer whose architecture contains several CPU chips arranged in parallel. Often used in image processing systems.

A method of measuring distance by recording a single scene from two points of perspective. Surveying instruments can be used; in autofocus systems, rangefinders and three-dimensional imaging systems,...

A color-television viewing system with three kinescopes, three lenses and three deflection yokes used to form the red, green and blue images required for a tricolor television projection.

A compound lens consisting of two negative lenses of flint glass. A double-convex lens of crown glass is cemented between the two negative lenses. With this system, it is possible to decrease...

The values of the three standard or matching stimuli necessary to provide a match with the light under trial, in a specified trichromatic system.

The size of the field of view in the object space of an optical system as differentiated from that in the image space (apparent field).

Turbidity is a measure of the cloudiness or haziness of a fluid caused by the presence of suspended particles. These particles can include sediment, silt, clay, plankton, and other microscopic...

Simulation of atmospheric turbulence for laboratory experimentation purposes, achieved by creating an unstable vertical gradient temperature in a tank filled with water.

Twisted intramolecular charge transfer (TICT) is a phenomenon observed in certain organic molecules containing electron-donor and electron-acceptor groups that are linked together within the same...

This results from the simultaneous absorption of two photons, each having half the energy needed for excitation and requiring a high spatial and temporal concentration of photons. The ensuing...

A system used to measure very small displacement by electrical means.

A dark-field microscope used to view extremely small objects. These objects are suspended in a gas or liquid in an enclosure having a black background. A convergent pencil of bright light enters from...

Ultraviolet-C (UV-C) refers to a specific range of ultraviolet radiation with shorter wavelengths than those of visible light. UV-C radiation spans the electromagnetic spectrum with wavelengths...

Ultraviolet (UV) fiber optics refers to optical fibers that are designed and optimized for the transmission of ultraviolet light, which is electromagnetic radiation with wavelengths shorter than...

The field of photography concerned with the recording of subjects beneath the water with a watertight, water-resistant camera system.