Photonics Dictionary: P

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...

A thin film or coating that forms on various finished surfaces. On optical surfaces it usually denotes aging.

A technique used to generate a phase shift between reference and sample light beams. The phase shift can be performed through the use of a mirror that is moved along the optic axis by a piezoelectric...

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...

A broadband, visible picosecond probe pulse capable of measuring an entire absorption spectrum in one shot.

A transmission or reflecting grating with a flat or plane surface requiring a lens or concave mirror to focus the spectrum.

The generation of a grating on a flat surface by means of a series of interference fringes formed by a holographic process. See holographic grating.

A semiconductor material used in photodetectors, sensitive in the infrared up to 5 µm.

A device attached to the end of an alignment telescope that detects and calculates a plane mirror's rotation axis that is perpendicular to the line of sight. The device is adaptable for evaluation of...

A coating made up of particular birefringent materials having polarizing properties. It may be used, in some cases, to replace Polaroid or polarizing prisms.

The arrangement of two Porro prisms so that the inverted image formed by certain types of optical instruments is the same as the object. The first prism, which is set at 90° to the second, inverts...

In remote sensing technology, this represents the intensity of energy flow in the direction of wave propagation.

In a waveguide, the material in intimate contact with the cladding surface, applied to preserve the integrity of that surface.

A device that couples a light source to an optical fiber by projecting an image of the source and the fiber core onto a screen where they can be superimposed by micropositioners.

A film applied to a coated or uncoated optical surface primarily for protecting this surface from mechanical abrasion, from chemical corrosion, or from both. For example, a thin layer of silicon...

The ratio of the active core area of a fiber bundle to the total area at its light-emitting or receiving end.

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 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...

A saturated compound of carbon and hydrogen used as a liquid coating material for optical components in high-power laser applications. See liquid coating.

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...

One eyepiece of a set having equal distances from their mounting interface to their image plane, permitting freedom to interchange eyepieces without the need to refocus.

Totally coherent radiation is produced by a purely monochromatic point source. In the real world the energy will have a limited bandwidth and the point source will subtend some angle resulting in...

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...

A passive optical network (PON) is a telecommunications network architecture that uses optical fibers and passive optical components to provide high-speed broadband services to end-users. In a PON...

An OLED display formed by creating an array of OLED pixels connected by intersecting anode and cathode conductors arranged in rows and columns. Electrical power is passed through selected pixels by...

A device that determines the lens shape in the cutting or edging phase of fabrication. It also is used to denote the arrangement of markings on a reticle.

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.

In a fiber optic guided missile, the point at which the optical fiber pays out from the bobbin on which it is wound.

A thin, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter, for example, in a color camera; it is so thin that no perceptible image doubling...

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...

A five-sided prism containing two reflecting surfaces at 45° to each other, and two refracting faces perpendicular to the entering and emerging beams. The deviation angle of 90° is...

A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts: 1. the umbra, or the central, totally dark part of the shadow; and 2. the...

The apparent color, as seen by the human eye, as distinguished from color as a measurable property of light.

The analysis of retinal zones in which different hues can be detected. Also called campimetry.

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...

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...

A high-speed, narrow-field lens consisting of two achromats spaced about the aperture stop. Its uses include portrait photography and motion picture projection.

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...

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...