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Photonics Dictionary: P

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positron -> electron

A charged elementary particle of an atom; the term is most commonly used in reference to the negatively charged particle called a negatron. Its mass at rest is me = 9.109558 x 10-31 kg, its charge is...

photoelectron holography

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...

photoelectron microscopy

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...

photoelectron

Electron released in photoelectric activity.

plasma-cathode electron gun

An electron beam gun in which plasma that is generated within a low-voltage hollow-cathode discharge serves as the source of electrons.

photocoupler -> optoisolator

An optical coupling device that uses light to bridge the gap between incompatible wire communications systems. It contains an input amplifier, a light-emitting diode, a photodiode and an output...

photoelectric photometer

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

photoisolator -> optoisolator

An optical coupling device that uses light to bridge the gap between incompatible wire communications systems. It contains an input amplifier, a light-emitting diode, a photodiode and an output...

pair production

The production of a positron-electron pair by a photon having energy greater than one mega-electron-volt, whereby some of the photon energy is converted to the rest mass of the pair.

panoramic camera

A camera designed to form a continuous record of an expansive section of the horizon. The typical panoramic camera is mounted to rotate about a vertical axis. A slit opening in the film plane and the...

particle acceleration

Particle acceleration refers to the process by which charged particles, such as electrons or protons, gain kinetic energy and increase their velocity. This acceleration can occur in various natural...

Pauli exclusion principle

The number of electrons that can share a principal quantum number by preventing identity between any two electrons' four quantum numbers, thereby permitting the periodic arrangement of the elements.

Peltier cooler

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...

permanent magnetic focusing

The focusing of an electron beam by a magnetic field that permanently retains the majority of its magnetic properties.

perovskite

The term perovskite refers to a specific crystal structure commonly found in various materials. Perovskite structures have a cubic arrangement of oxygen ions, forming a framework within which other...

phosphor

A chemical substance that exhibits fluorescence when excited by ultraviolet radiation, x-rays or an electron beam. The amount of visible light is proportional to the amount of excitation energy. If...

phosphor light source

A source made to glow by electrons that are produced either electrically or by isotopes of various elements.

photobleaching

Photobleaching is a phenomenon in which the fluorescence of a fluorophore (a fluorescent molecule or dye) is permanently reduced or eliminated upon prolonged exposure to light. This process occurs...

photocathodes

Photocathodes are specialized materials or surfaces that exhibit the photoelectric effect, wherein the absorption of photons leads to the emission of electrons. When photons with sufficient energy...

photochemical

The term photochemical pertains to chemical processes or reactions that are initiated or influenced by the absorption of light. Photochemical reactions involve the interaction of light, often in the...

photochromic

Photochromic refers to a property exhibited by certain materials, typically organic compounds or dyes, which undergo reversible changes in color when exposed to light. Specifically, photochromic...

photoconductivity

The conductivity increase exhibited by some nonmetallic materials, resulting from the free carriers generated when photon energy is absorbed in electronic transitions. The rate at which free carriers...

photodetector

A photodetector, also known as a photosensor or photodiode, is a device that detects and converts light into an electrical signal. Photodetectors are widely used in various applications, ranging from...

photodiode detector

A photodiode detector is a semiconductor device that converts light into an electrical current. It operates based on the principle of the photoelectric effect, where photons of light incident on the...

photoelectric constant

The constant that, multiplied by the frequency of the radiation-producing emission of photoelectrons, determines the amount of voltage each photoelectron absorbs.

photoelectric counter

A device used to count objects that pass a given point by allowing each object to obstruct a beam of light falling on a photocell. Slow counting rates can be recorded by a mechanical counter, but...

photoelectric current

The electron stream emitted by a phototube when the cathode is exposed to light.

photoelectric effect

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.

photoelectric emission

The electron emission from a substance or instrument whose surface has been bombarded by a suitable amount of radiation.

photoelectric sensitivity

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

photoelectric tube -> phototube

An electron tube having a photocathode for the emission of a photoelectric current.

photoemission -> photoelectric emission

The electron emission from a substance or instrument whose surface has been bombarded by a suitable amount of radiation.

photoemissive cell -> photoemissive detector

An electronic tube instrument in which the anode current varies with the intensity of light incident on the cathode.

photoemissive detector

An electronic tube instrument in which the anode current varies with the intensity of light incident on the cathode.

photoemissive effect -> photoelectric effect

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.

photolithography

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

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...

photomask

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...

photomultiplier tube

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,...

photonic computer

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...

photonic crystal surface-emitting laser

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

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...

photonic integrated circuit

A photonic integrated circuit (PIC) is a compact and integrated device that incorporates multiple photonic components and functions on a single chip, similar to the way electronic integrated circuits...

photonics

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...

photoreflectance

A noncontact form of electromodulation in which modulation of the electric field is caused by photo-excited electron-hole pairs from a pump source.

photoresist

Photoresist is a light-sensitive material used in photolithography processes, particularly in the fabrication of semiconductor devices, integrated circuits, and microelectromechanical systems (MEMS)....

photosensitive recording

The recording achieved when a surface, illuminated by a signal-controlled light beam, emits electrons or reacts in some manner.

photosurface

The surface from which electrons are ejected by the incidence and absorption of photons.

phototube

An electron tube having a photocathode for the emission of a photoelectric current.

photovoltaic cell

A photovoltaic cell, commonly known as a solar cell, is a semiconductor device that directly converts light energy into electrical energy through the photovoltaic effect. The photovoltaic effect is...

Photonics DictionaryP