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Bristol Instruments, Inc. - 872 Series High-Res 4/24 MR

711 terms

Photonics Dictionary: P

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packing density

1. In a photonic interconnect, the number of detectors in a given area. Detectors spaced too closely may give rise to crosstalk. 2. In the cross section of a fiber optic bundle, the ratio of fiber...

panchromatic sensitivity

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

panoramic lens

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...

paraboloidal condenser

A condenser composed of a paraboloidal reflector and used for dark-field illumination.

parallel transmission

A mode of data transmission whereby bits of information are carried simultaneously at different frequencies over a single channel.

parfocal lenses

Lenses that have identical flange focal distances and can be interchanged.

perfect lens

A theoretical, ideal lens capable of producing perfect images. Used as a lens design and analysis tool to image collimated output from an afocal system.

peripheral response

In a charge-coupled device, the detection of charge collected by the transport register rather than by the image-sensing elements.

periscopic lens

Two simple meniscus lenses arranged symmetrically on either side of the aperture stop, providing reduced coma, lateral color and distortion.

Petzval lens

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

phase constant

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 transfer function

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...

phase translation

The propagation or hindrance of waves reaching each aperture of the interferometer because of atmospheric turbulence.

phase-modulated sensor

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...

photocathode luminous sensitivity

The responsivity of a photocathode to luminous energy equal to the ratio of the photoelectric emission to the incident luminous flux.

photoelastic constant

A formulaic description of the linear change of the reciprocal optical dielectric tensor with either stress or strain.

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 densitometer -> densitometer

1. An instrument used to measure the opacity or density of dyes, pigments or dispersed particles that form an image in or on a medium, such as a photographic film. 2. A device used to measure the...

photoelectric sensitivity

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

photographic sensitometer -> sensitometer

An instrument for determining the sensitivity of a photographic film to light. The film is given either a stepped exposure or a continuously varied exposure; after processing, the density is measured...

photographic sensitometry

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

photoresponse nonuniformity

Noise created by patterns imaged on a CCD surface. Pixel sensitivity is altered by responsivity during illumination.

photosensitive recording

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

photosensitivity

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

photosensitizer

A substance that increases a material's sensitivity to electromagnetic irradiation. In photodynamic therapy, a drug used to render a target tissue sensitive to laser light.

phototransistor tachometer

A tachometer consisting of a light source, rotating perforated wheel and phototransistor to measure the rates of rotation of components. The phototransistor counts the flashes formed when the wheel,...

phototransistor

A phototransistor is a type of semiconductor device that converts light energy into electrical signals. Similar to a regular transistor, it consists of a semiconductor material (such as silicon) with...

piezo-optical transducer

A structure consisting of a thin film of liquid crystal sandwiched between light-polarizing filters that have received a surface lubricant. Depending on motion, the transducer acts as a highly...

piezoelectric transducers and ceramic materials

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...

Planck's constant

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.

plane densitometer

An instrument designed to give precise and rapid detection of changes in tumor growth as well as the location of small tumors by providing a three-dimensional picture of the tissue.

plano lens -> window

1. A piece of glass with plane parallel surfaces used to admit light into an optical system and to exclude dirt and moisture. 2. A particular region of the electromagnetic spectrum that has been...

planoconcave lens

A lens with one plane surface and one concave surface.

planoconvex lens

A lens that has one plane surface and one convex surface.

plastic lens

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...

polarization-insensitive operation

Capability requirement for optical switches for transmission lines to process arbitrarily polarized light because of the rapid changes in the polarization state of light propagating in the fibers.

positive-intrinsic-negative diode -> PIN photodiode

A PIN photodiode is a type of photodetector or semiconductor device used to convert light signals into electrical signals. The name "PIN" is derived from the arrangement of the three semiconductor...

power density

In laser welding or heat treating, the instantaneous laser beam power per unit area. This parameter is key in determining the fusion zone profile (area of base metal melted) on a workpiece.

process lens

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...

propagation constant

For an electromagnetic field mode varying sinusoidally with time at a given frequency, the logarithmic rate of change, with respect to distance in a given direction, of the complex amplitude of any...

proximity-mode sensing

A method of sensing by transmitting energy from the sensor and detecting the energy after it has been reflected by the object in its path.

passive optical network

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...

permittivity -> dielectric constant

A number that indicates the magnitude of the shift in a solid of positive and negative charges in opposite directions when a voltage is applied across the solid.

phase screen

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...

phonon

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...

photosynthetically active radiation

Photosynthetically active radiation (PAR) is the 400- to 700-nm region (visible light) of the electromagnetic spectrum that is absorbed and used by the plant for photosynthesis. Also referred to as...

plane table -> surveying instruments

Instruments used for measuring angles and occasionally lengths on the ground. The principal surveying instruments are the level, the stadia telescope, the transit and the theodolite. Laser...

pluggable optics

Pluggable optics, also known as pluggable transceivers or optical transceivers, are modular devices used in optical communication systems to transmit and receive data over optical fibers. They are...

P-type conductivity

In a semiconductor, the state created by the addition of a dopant that creates excess holes.

P-type material

A semiconductor material in which the dopants create holes as the majority charge carrier. It is formed by doping with acceptor atoms.

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