Photonics Dictionary: P

A prism made up of two air-spaced components. It has the ability to revert, and not invert, an image, and can be used in convergent, divergent and parallel light. May be rotated to compensate for...

The wavelength at which a lamp radiates its highest intensity.

The distortion that is the result of viewing a print from a point other than the center of perspective. The center of perspective is that viewpoint at which the angular subtenses of points in the...

The grinding and polishing of rock samples, to a thickness of less than 0.05 mm, for study with petrographic microscopes. When mounted on a slide and protected with a cover, these samples, examined...

The spectroscopic study of the radiation emitted by the lifetime of phosphorescence.

A method for obtaining the optical absorption spectra of solids, semisolids, liquids and gases. PAS is inherently insensitive to reflection or scattering from the sample, analyzes opaque samples and...

A spectroscopic process that detects and analyzes the discharge from an extrinsic surface with less than bandgap light. This method may determine the extrinsic surface-state energy levels of a...

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

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...

A method of measuring complex sequential photosynthetic reactions by varying the pulse time and wavelength of light generated by a combination of argon-ion and dye lasers.

A filtering method that restores a blurred image by setting its power spectrum equal to that of the original image.

The first-order spectrum formed by a diffraction grating.

The spectrum formed by a dispersing prism or a dispersing prism system.

Color sensitivity extended to cover the entire visible spectrum out to the red.

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...

Parallel scanning refers to a method of acquiring data or images simultaneously from multiple sources or in parallel, rather than sequentially scanning each source one after another. This approach is...

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,...

A mounting used for large concave gratings, whereby the slit, grating and plate holder lie in the Rowland circle, and the photographic plates lie along a large portion of the circle. In this way, a...

Passive optical components are devices or elements used in optical systems that do not require external power or active control to perform their function. These components manipulate light signals...

The criterion maintaining that if light follows a specific path through an optical system, it will, if reversed, traverse that same path in the opposite direction.

Pathogenesis refers to the process by which a disease develops and progresses within an organism. It encompasses the sequence of events and mechanisms that lead to the onset, progression, and...

A form of dispersing prism, often used in monochromators, that consists of a common right-angle prism with a 30° dispersing prism attached to each of its square faces. The spectrum formed by the...

A pentaprism is a five-sided glass prism used in optical devices, particularly in SLR cameras, to deviate the path of light by 90 degrees and ensure that the image seen through the viewfinder is...

An optical instrument designed to displace the line of sight in a vertical direction. For submarines and other military uses the periscope is a long tube containing prisms at both ends and...

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...

A phage, short for bacteriophage, is a type of virus that infects and replicates within bacteria. Phages are composed of genetic material (either DNA or RNA) surrounded by a protein coat. They are...

In optics and photonics, "phase" refers to a property of electromagnetic waves, such as light, that describes the position of a wave at a given point in time within its oscillation cycle. More...

A term for the ring-shaped stop in a phase contrast microscope. The phase annulus limits the amount of light that reaches the phase plate from the direction of the specimen and retards the light by a...

With respect to a traveling plane wave at a known frequency, the space rate of decrease of phase of a field component in the direction of propagation, measured in radians per unit length.

Phase contrast microscopy is an optical microscopy technique that enhances the contrast of transparent and colorless specimens, making it possible to visualize fine details and internal structures...

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...

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...

The determination of the relative phase shift of an image as a function of frequency. A phase change of 180° with respect to the object results in an image with the black and white areas...

Microscopy technique to convert the phase structure of the wave transmitted or reflected by the specimen into a corresponding intensity structure in the image plane.

A phase-modulated sensor is a type of sensor that uses modulation of the phase of a signal to measure changes in a physical quantity. In such sensors, variations in the phase of the signal are...

A phonon is a quantum of vibrational energy associated with the periodic motion of atoms or molecules in a crystalline lattice. In simpler terms, phonons are quanta of lattice vibrations in a solid...

Photoacoustic refers to the generation of acoustic (sound) waves following the absorption of light (usually laser pulses) by a material. This phenomenon occurs when light energy is absorbed by a...

A light therapy that utilizes nonionizing light sources, including lasers, LEDs, and broadband light, in the visible and infrared spectrum. It is a nonthermal process involving endogenous...

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...