Photonics Dictionary: P

The emission of an electron from a surface that occurs when a photon impinges upon the surface and is absorbed. This effect is the means by which photons may be detected.

A device consisting of a microammeter, a photovoltaic cell and a battery. It is used for the measurement of scene brightness and the determination of correct exposure for photographic processes.

A phototube in which the primary photoemission current, before being extracted at the anode, is multiplied many times.

Also known as electronic photometer. A photometer with a photocell, phototransistor or phototube for measuring the intensity of light.

The use of photoelectric sensors to detect and measure the intensity of a light source. This application, as compared to human observation, results in higher speeds of operation, a greater...

An instrument used to measure the temperature of a source through the use of photoelectric cells to detect and measure the intensity of the light emitted by the source.

An instrument that uses a photocell to detect and measure the intensity of incident light.

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...

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

The force that stimulates the emission of an electrical current when photovoltaic action creates a potential difference between two points.

A technique proposed for studying the atomic structure of crystals by measuring the interference pattern generated when the crystal is illuminated by a burst of finely tuned x-rays. The resulting...

Surface analysis by means of photon induced electron emission. PEM methods provide high lateral resolution of the observed sample.For surface material sciences PEM allows the investigation of...

A particular type of phototube having increased sensitivity as a result of the glow initiated by light incident to the cathode.

Photogrammetry is a technique used to obtain accurate three-dimensional measurements of objects and environments through the analysis of photographs or imagery. It involves extracting information...

A form of photometric measurement, often used with light sources that are transparent or fluctuating, in which a photographic plate is used to obtain a record of a source's relative intensities over...

The use of photographic recording equipment to measure radiant energy. With this procedure, many measurements of radiant energy can be recorded simultaneously and permanently.

A system in which the electrical signal embedded within an audio input signal is converted to a modulated light pattern and recorded on film.

The photographic recording of the heat radiation emitted from various points on the object as corresponding density variations on fast infrared film.

Photoimmunotherapy (PIT) is a medical treatment approach that combines elements of phototherapy and immunotherapy to target and treat specific cells or tissues in the body. The key components of this...

Photolithography is a key process in the manufacturing of semiconductor devices, integrated circuits, and microelectromechanical systems (MEMS). It is a photomechanical process used to transfer...

Photoluminescence is a phenomenon in which a material absorbs photons (light) at one wavelength and then re-emits photons at a longer wavelength. This process occurs when electrons in the material...

A photomask, also known simply as a mask or reticle, is a key component in the photolithography process used in semiconductor manufacturing and other areas of microfabrication. It is a high-precision...

A device used to compare the luminous intensities of two sources by comparing the illuminance they produce.

Pertaining to the measurement of the intensity of light.

Photocells of various kinds used to measure photometric quantities; i.e., intensity, luminance and illuminance. Meter readings are used to express illuminance and, by calibration, to measure...

Photometry is the branch of science that deals with the measurement of light, particularly in terms of its intensity and the way the human eye perceives it. It involves the quantification of visible...

A photomicrograph is an image taken through a microscope, typically using a camera attached to the microscope's eyepiece or an integrated digital imaging system. It captures the magnified view of...

A still or motion-picture camera designed to photograph through a microscope. Photomicrographic equipment usually contains a beamsplitter or other means for simultaneously viewing, orienting and...

A photomultiplier tube (PMT) is a highly sensitive vacuum tube that detects and amplifies low levels of light. It is widely used in various applications where high sensitivity, fast response times,...

A quantum of electromagnetic energy of a single mode; i.e., a single wavelength, direction and polarization. As a unit of energy, each photon equals hn, h being Planck's constant and n, the frequency...

Spectroscopy used to study the concentration, diffusion and Brownian motion of small particles suspended in a fluid by measuring dynamic fluctuations of light that is scattered or fluoresced by the...

An infrared detector in which radiation passes through a doped germanium crystal, creating a voltage drop that can be measured in terms of incident intensity.

Photon flux refers to the rate at which photons (particles of light) pass through a unit area per unit time. It is a measure of the intensity or brightness of light in a specific region of space or...

A photon jet is a narrow, highly collimated beam of light that is formed when light interacts with small dielectric microstructures, such as microspheres or microcylinders. This phenomenon arises due...

An instrument in which visible light beyond the critical angle from a metallurgical microscope is focused on a reference surface. A certain fraction of the incident light tunnels through air to the...

Photon-rich typically refers to an environment or situation where there is an abundance of photons present. In the context of optics, photon-rich environments are those where there is a high density...

The property exhibited by a substance having electrical conductivity that decreases as the intensity of the incident visible radiant energy increases.

A type of computer in which the electronic circuits, which process data serially, are replaced by photonic circuits capable of parallel processing and thus of much greater speed and power. Where the...

A photonic crystal surface-emitting laser (PCSEL) refers to a type of laser diode that emits light from its surface rather than from the edges. Photonic crystals are periodic nanostructures that...

Photonic crystals are artificial structures or materials designed to manipulate and control the flow of light in a manner analogous to how semiconductors control the flow of electrons. Photonic...

A photonic engine refers to a device or system that utilizes photonics, or the science and technology of generating, controlling, and detecting photons (particles of light), to perform various...

The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and...

A photonic cavity, also known as an optical cavity, is a structure that confines electromagnetic radiation within a certain region or volume. It is typically composed of materials with different...

Photonics contract manufacturing refers to the outsourcing of the production of photonics-related components, devices, or systems to specialized manufacturing firms. Photonics involves the...

Photoplethysmography (PPG) is a non-invasive optical technique used to detect changes in blood volume in tissues. It measures variations in light absorption caused by the pulsatile nature of blood...