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598 terms

Definitions: P

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polychromatic acousto-optic modulator
A crystal-based device that combines and adjusts the intensities of multiple wavelengths of laser light in order to obtain the desired output wavelength.
polychromatic illumination
Light that is a mixture of wavelengths.
polychromatism -> dichroism
Dichroism refers to the property of certain materials to exhibit different colors or absorbance of light depending on the direction of light propagation or polarization. The term is commonly used in...
polycrystal
A substance that transmits the infrared, but which is too delicate or fragile to be used in the form of a single crystal. Instead, the pure material is finely ground, pressed to the required shape,...
polyethylene
A material used to jacket fiber optic cables. It is chemical- and moisture-resistant, but not fire-resistant.
polygonal mirror
A polygonal mirror, also known as a multifaceted mirror or facet mirror, is a type of optical component used in various laser systems, optical scanners, and imaging devices. It consists of a flat or...
polymer
Polymers are large molecules composed of repeating structural units called monomers. These monomers are chemically bonded together to form long chains or networks, creating a macromolecular...
polymerase chain reaction
The polymerase chain reaction (PCR) is a widely used molecular biology technique used to amplify a specific segment of DNA (deoxyribonucleic acid) through a series of temperature-controlled cycles....
polymerization
Process of synthesizing long molecular chain materials (polymers) by reaction of many small molecules (usually thousands) called monomers.
polymethyl methacrylate -> acrylic
A thermoplastic or optically transmitting hard plastic produced by applying polymerization initiator and heat to a monomer.
polystyrene
A plastic used in molded optical components. Styrene elements can be combined with acrylic elements to produce achromatic lenses.
polysulfone resin
A thermoplastic, self-extinguishing polymer with excellent high-temperature, low-creep and arc resistance properties.
polyvinyl alcohol
An optical-quality polymer used in birefringent retarders.
population inversion
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...
Porro prism
A 45-90-45° reflecting prism whose surfaces form the 90° angle reflecting the light beam through a total angle of 180°. The corners of the prism are rounded to minimize breakage and simplify...
Porro prism erecting system
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...
positioning
Positioning generally refers to the determination or identification of the location or placement of an object, person, or entity in a specific space or relative to a reference point. The term is used...
positive crystal
A uniaxial, birefringent crystal having an ordinary ray with a higher velocity than the extraordinary ray.
positive dielectric anisotropy
The dielectric coefficient parallel to the director in a liquid crystal display (LCD), rather than perpendicular to the director.
positive spherical aberration -> spherical aberration
Spherical aberration is an optical aberration that occurs when light rays passing through a lens or curved optical surface do not converge or diverge to a single focal point. Instead of focusing to a...
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...
positron -> electron
A charged elementary particle of an atom; the term is most commonly used in reference to the negatively charged particle called a negatron. Its mass at rest is me = 9.109558 x 10-31 kg, its charge is...
positron emission tomography
A medical imaging device that uses a ring of crystal/photomultiplier tube assemblies encircling the patient to detect gamma rays emitted by positrons colliding with electrons.
positronium
Basically, a hydrogen atom with two alterations, positronium is the lightest atom in the universe and has an extremely light positron in its nucleus that replaces hydrogen's proton so that its atomic...
posterization
In image processing, the effect caused by large jumps between gray levels, rather than a gradual change.
potassium titanyl phosphate
A crystalline material with a high electro-optic coefficient, capable of operating at short wavelengths, with applications in laser, optical disc, printing and microwave systems.
potentiometer
A device designed to measure electromotive force or electrical difference potential.
potting -> imbedding material
A thermoplastic or thermosetting material used to hold an object fixed and keep it from deterioration. In microcircuitry, the process of imbedding is known as potting.
powder camera
A camera system that uses a fine powder to diffract x-rays from the specimen. A beam of monochromatic x-rays passes through a collimator onto the specimen. Diffracted x-rays are recorded on the film...
powder radiography
A technique used in radiography to determine a crystal's structure by obtaining radiographs of it in powder form, normally by the use of a powder camera that forms an image of the crystal's x-ray...
power
With respect to a lens, the reciprocal of its focal length. The term power, as applied to a telescope or microscope, often is used as an abbreviation for magnifying power.
power average
For a pulsed laser, the product of the energy per pulse (joule) and the pulse frequency (hertz); expressed in watts.
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.
power efficiency
The ratio of emitted power to input power.
power flow equation
Optical fiber channel characterization scheme based on three assumptions; the discrete mode spectrum can be replaced by a continuum; the loss due to coupling between guided and radiation modes...
power modulation
Power modulation refers to the intentional variation of power levels in a signal, often in the context of electronic communication systems. This modulation technique is used to encode information...
power ratio -> radiant power
The time rate of flow of radiant energy, expressed in watts (W), and carries the units of Joule per second (J/s). The prefix often is dropped and the term "power" used.
power scanning laws
Laws that predict the maximum power output as a function of tube diameter for a hydrogen cyanide laser of a given discharge length and cavity losses, all other parameters being optimized.
power spectrum equalization
A filtering method that restores a blurred image by setting its power spectrum equal to that of the original image.
power supply
Refers to the voltage and current necessary for the operation of circuit devices.
Poynting vector
In remote sensing technology, this represents the intensity of energy flow in the direction of wave propagation.
PP junction
A transition boundary between two regions having different properties in a P-type semiconducting material.
Prandtl number
Ratio of the molecular diffusion coefficients of momentum in terms of heat; used in convection studies.
precision aperture
An accurately produced hole of any size and shape that is used as a masking device in an optical system. Pinhole apertures of accurate diameters often are produced by laser beam penetration or by...
preform
A glass structure from which an optical fiber waveguide may be drawn.
prefusing
A step before fusion splicing that involves cleaning the fiber end with low-current electricity.
prelasing
When uncontrolled laser energy leaks from a laser cavity prematurely, it causes serious damage to optical components and significant downtime for repair.
Prentice's rule
A method of determining prism power at any point on a lens. Prism power equals the product of the dioptric power and the distance, in centimeters, from the optical center.
presbyopia
A state in which the human eye has very little or no power of accommodation. A common and normal condition in the eyes of those age 50 and older.
pressing
A blank having basic surface curves attained by forming heat-softened glass that is pressed in a mold.

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