8,289 terms
Photonics Dictionary
Clear All Filters xns x
path length -> optical path lengthIn a medium of constant refractive index, the product of the geometrical distance and the refractive index.
path-reversal principleThe 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.
pathogenA pathogen is a biological agent, such as a virus, bacterium, fungus, protozoan, or parasite, that causes disease in its host organism. Pathogens have the capability to invade host tissues,...
pathogenesisPathogenesis 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...
patinaA thin film or coating that forms on various finished surfaces. On optical surfaces it usually denotes aging.
patternA 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.
Pauli exclusion principleThe 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.
PBproton bombardment
PBCpolarization beam combiner
PBXprivate branch exchange
PCphotoconductive; printed circuit; personal computer
PCAphotoconductive antenna
PCEphase-change erasable
PCFphotonic crystal fiber
PCIperipheral component interconnect
PCMpulse code modulation; phase-conjugate mirror
PCRphotoconductive relay; polymerase chain reaction
PCSplastic-clad silica; photon correlation spectroscopy
PCTphoton-coupled transistor
PCVDplasma chemical vapor deposition
PDAphotodiode array; postdeflection acceleration
PDCRpolarization-dependent coupling ratio
PDGpolarization-dependent gain
PDKphase-delay keying
PDLpolarization-dependent loss
pdlpoundal
PDMpulse duration modulation
PDPparallel detection polychromator
PDTphotodynamic therapy
PEprocessing element
peak spectral emissionThe wavelength at which a lamp radiates its highest intensity.
peak wavelengthThe wavelength at which the radiant intensity of a source is maximum.
Pechan prismA 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...
pedestal componentPresent in photocurrent burst, it is the low frequency pulse that corresponds to the light scattered from the beams in the absence of heterodyne mixing.
peel pointIn a fiber optic guided missile, the point at which the optical fiber pays out from the bobbin on which it is wound.
pelContraction of "picture element." See pixel.
pellicle mirrorA 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...
Pellin-Broca prismA 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...
Peltier coolerA 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...
Peltier effectSee thermoelectric cooling.
PEMphotoelectromagnetic
pencil beamIn astronomy, the main lobe of an antenna pattern that has a small angular extent in two mutually perpendicular directions. Invisible in space, it would resemble a searchlight beam.
Penning dischargeA standard source of high-charge-state ions for accelerators that has an external magnetic field oriented perpendicularly to the two cathode faces. Also called Philips ionization gauge.
penta prismA 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...
pentamirrorA pentamirror is an optical component found in SLR cameras, composed of multiple flat mirrors arranged in a pentagonal configuration. Its primary function is to redirect light from the camera lens to...
pentaprsimA 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...
penumbraA 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...
perceived colorThe apparent color, as seen by the human eye, as distinguished from color as a measurable property of light.
perfect crystalA crystalline substance in which all planes are parallel, or approximately parallel.
perfect diffuserA surface that obeys Lambert's cosine law and has a reflectance of unity.
Photonics Dictionary