Photonics Dictionary

A photoelectric photometer used to measure the reflectance of a surface.

A relay that opens or closes an electrical circuit depending on the intensity of the light incident to a photoelectric device contained in the relay.

A system mounted a few inches above a moving plane that consists of a light source, lenses and one or more phototubes. In this position, the scanner actuates the control equipment when the quantity...

That property of a material that determines its ability to release electrons when absorbing photons.

A system that consists of a spectrophotometer with a photoelectric detector for measurement of radiant energy.

With respect to a crystal, one of the paths or axes that will exhibit a piezoelectric charge when subject to tension or compression.

A crystal consisting of a substance that has the ability to become electrically polarized and has strong piezoelectric properties. It is cut so as to emphasize the coupling to some distinct...

The interaction between electrical and mechanical stress-strain factors in a material. When piezoelectric crystal is compressed, an electrostatic voltage is generated across it, or when an electric...

Piezoelectric motion systems are mechanical systems that utilize piezoelectric materials to generate controlled motion or displacement. Piezoelectric materials exhibit the piezoelectric effect, which...

Piezoelectric transducers are devices that utilize the piezoelectric effect to convert electrical energy into mechanical vibrations or vice versa. The piezoelectric effect is a property exhibited by...

The dielectric coefficient parallel to the director in a liquid crystal display (LCD), rather than perpendicular to the director.

Unlike the thermocouple or bolometer, the pyroelectric infrared detector is a current source with an output proportional to the rate of change of its temperature. Capable of extremely rapid response...

A current-source thermal detector used to detect and study the pulses obtained from particular lasers.

A waveguide with a rectangular cross section that is composed entirely of dielectric materials.

Characteristic of the relationship between photoelectric activity and the wavelength of incident radiation.

An instrument that transforms heat energy into electrical energy.

A refrigeration method based on the Peltier effect. When an electric current passes through a thermocouple of two dissimilar metals joined in two places, heat is absorbed at the cold junction and...

A solar cell that uses a thermoelectric converter, consisting of two sheets of metal with a semiconductor sandwiched between them, to generate electricity.

The magnitude of the electric vector of a wave of light. See electric vector; magnetic vector.

In the context of electronics and optics, an isolator refers to a device that allows the transmission of signals in one direction while attenuating or blocking signals in the opposite direction. The...

A Peltier cooler, also known as a thermoelectric cooler (TEC) or thermoelectric module, is a solid-state device that uses the Peltier effect to transfer heat between two electrical junctions. It can...

See thermoelectric cooling.

An optical lens manufactured to control the transmission of light over a specified wavelength range. Low absorption lenses are produced which are anti-reflection coated for UV, VIS and IR wavelengths...

An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms, it measures acceleration. Accelerometers are widely used in various...

Optic surface cleaning liquid that may be applied to glass, crystal, dielectric and metal surfaces; however, may not be applied to plastic and polymer materials.

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 disordered, glassy solid state of a substance, as distinguished from the highly ordered crystalline solid state. Amorphous and crystalline phases of the same substance differ widely in optical...

An operational mode for radiometers that analogs the method of operation of an angstrom pyrheliometer. In this mode, the rearward-facing cavity is electrically heated, while the forward cavity is...

Anisotropic is a term used to describe a material or substance that exhibits different properties or behaviors in different directions. In other words, the physical or mechanical characteristics of...

Anisotropy refers to the property of exhibiting different values or characteristics when measured in different directions. In various fields, including physics, materials science, and geology,...

The process of heating and slowly cooling a solid material, like glass or metal, to stabilize its thermal, electrical or optical properties or, as in semiconductor materials, to reverse lattice...

The part of an electrical circuit in which the electrons leave (a cathode-ray tube) or enter (an electrolytic cell) a unit in the circuit.

An electrically conductive layer for carrying off static charges that might accumulate on a surface.

An APD detector, or avalanche photodiode detector, is a type of photodetector used to detect light or optical signals by converting incoming photons into electrical current. It operates based on the...

The electric arc that is a particular discharge between two electrodes in a gas or vapor which is characterized by high cathode densities and a low voltage drop.

An arc flash is a sudden release of electrical energy due to an electric arc — a continuous, high-current discharge of electricity between conductors or from a conductor to ground. Arc flashes...

The spectrum of the light produced by vaporizing an element in an electric arc.

An atomic force microscope (AFM) is a high-resolution imaging and measurement instrument used in nanotechnology, materials science, and biology. It is a type of scanning probe microscope that...

The indistinct, less luminous portion lying immediately outside an electric arc whose spectrum often differs from that of the core.

1. In astronomy, the angle measured clockwise (eastward) in a horizontal plane, usually from north (true north, Y-north, grid north or magnetic north). 2. With relation to the plane-polarized light...

Azimuthal polarization refers to a specific polarization state of light where the electric field vector of the electromagnetic wave points along the azimuthal direction (around the propagation axis)....