Photonics Dictionary: P

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...

A concave mirror that has the form of a paraboloid of revolution. The paraboloidal mirror may have only a portion of a paraboloidal surface through which the axis does not pass, and is known as an...

An array of lines in the infrared region of the emission spectrum of atomic hydrogen. Their wave numbers are expressed by the equation: where represents the wave number in the reciprocal centimeters,...

Phase distortion refers to a change in the phase relationships between different frequency components of a signal. In the context of signal processing, it occurs when the phase response of a system...

A hologram that is formed on a recording medium by changing the phase of the illuminating wave in correspondence with the recording exposure. It may be formed by contact printing onto a resist...

In optics and photolithography, a phase mask refers to a device that modifies the phase of light waves passing through it. The phase mask is used to control the spatial distribution of the light's...

A phase screen, in the context of optics and wave optics, refers to a surface or medium that introduces a phase delay to an incident wavefront passing through it. This concept is often used in the...

In biology, particularly genetics and evolutionary biology, the phenotype refers to the observable characteristics or traits of an organism, resulting from the interaction of its genetic makeup...

A process used in pyrometry and photothermometry to create a photographic record of a surface's temperature gradients. Essentially, it involves the exposure of a glowing phosphorescent surface to the...

Periodic interruptions of a light beam incident on an absorbing medium that produce heat, expansion and acoustic wave generation. Since the amplitude of this wave is proportional to the absorbed...

Generation of an acoustical signal by a sample exposed to modulated light.

Abbreviated PAI. An imaging modality with a hybrid technique based on the acoustic detection of optical absorption from endogenous chromophores or exogenous contrast agents. Light is absorbed by the...

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 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...

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...

The current that flows through a photosensitive device, such as a photodiode, as the result of exposure to radiant power.

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...

The potential difference between two areas of a semiconductor when one is exposed to light.

Photodynamic inactivation (PDI) is a therapeutic approach that utilizes the combination of light, a photosensitizer, and molecular oxygen to induce cell death or inactivate microorganisms. This...

Photoelastic equipment and supplies refer to instruments and materials used in photoelasticity, a technique used to analyze stress distribution and behavior in materials. photoelastic equipment...

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

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.

Interaction of a magnetic field with a photoconductive substance exposed to light to create a potential difference.

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...

The use of photographic emulsions to detect and determine the amounts of ionizing radiation, such as x-rays and gamma rays, in an area. This is accomplished by exposing the emulsion to the radiation...

The product of exposure time and irradiance or illuminance.

The measurement of the responsivity of photographic media and of the relations between exposure and density of developed images.

A measure of the total light passed by a shutter during an exposure, compared with the light that could be passed by an idealized, infinitely fast shutter fully open for the same extreme time.

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...

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...

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 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,...

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

A holographic plate coated by photopolymeric mixtures that are composed of one or more monomers and a photoredox catalyst sensitized to visible light. The material becomes a plastic solid when...

A process in which a mixture of one or more monomers, plus a catalyst, polymerize under exposure to light radiation. Photopolymerization permits a hologram to be exposed, fixed and reconstructed in...

A material in which the refractive index varies according to changes in the light to which it is exposed. Lithium niobate is one example.

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

That property of a material indicating that it will react when exposed to light energy.

The photographic recording of data, in binary form, for storage in memory. Exposure is achieved by a cathode-ray tube or by modulating a continuous-wave laser beam with a Kerr cell, both relative to...

A camera equipped with angular scales in altitude and azimuth. The scale readings are imprinted on the film when an exposure is made. The exact point indicated by the scale readings is shown by...

Phototherapy is a medical treatment that involves the use of light to treat various conditions, particularly those related to the skin or mood disorders. There are different types of phototherapies,...

The cause of some forms of laser injury in which tissue absorbs incident laser light and experiences a damaging rise in temperature. The severity of the damage is dependent on the rate of energy...

Phototoxicity refers to the harmful effects caused by exposure to light, particularly intense or ultraviolet (UV) light, on living cells or organisms. This phenomenon is often associated with the...