Photonics Dictionary: P

A lens system that is capable of producing a 360° image, or one that is very close to that. In recording, the image may be formed on a curved strip of film surrounding the lens, resulting in a...

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,...

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 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...

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 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...

A two-electrode, radiation-sensitive junction formed in a semiconductor material in which the reverse current varies with illumination. Photodiodes are used for the detection of optical power and for...

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...

Participates in a reaction only in the presence of light and radiant energy. Besides 3D printing, photoreactive agents also have an application in light therapy. By absorbing light, photoreactive...

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...

A pulse having extremely short duration, about 10-13 to 10-10 s, that is produced by mode locking of wide-bandwidth lasers, such as the organic dye and ruby lasers. Picosecond pulses are used in the...

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 formula describing the spectral radiant emittance of a perfect blackbody as a function of its temperature and the wavelength of the emitted radiation. where Wλ equals radiation...

The universal constant h that has a value of 6.6260693 x 10-34 Js. A quantum of energy is equal to the product of the frequency of the radiation and Planck's constant.

A lens made from transparent plastic material. Lenses over 31/2 in. in diameter are usually machined, ground and polished. Smaller lenses are usually injection molded, the mount surrounding the lens...

A Pockels cell, also known as an electro-optic modulator, is an optical device used to control the polarization of light by applying an electric field. It is named after the physicist Friedrich Carl...

A point cloud is a set of data points in a three-dimensional coordinate system, where each point represents a specific location in space. These points are typically obtained through various sensing...

The condition in which there are more atomic systems in the upper of two energy levels than in the lower, so stimulated emission will predominate over stimulated absorption. This condition may be...

A lens that is symmetrical and designed to work between 1:1 and about 4:1. It covers a field of about ±20° at f/8 or f/10, and may have a focal length up to about 30 in., although the usual...