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Photonics Dictionary: R

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radiant flux density -> irradiance
Radiant flux incident per unit area of a surface. Also called radiant flux density.
radiant intensity
The radiant energy emitted within a time period per unit solid angle, usually measured in watts per steradian.
radiation dosimetry
The detection and measurement of nuclear and x-ray radiation.
real-time processing
The ability of a vision system to interpret an image in a short enough time to keep pace with most operations.
rear focusing
A type of internal focusing in which only the lens elements closest to the rear of the lens barrel are moved.
region-of-interest processing
Image processing operations performed on one area of an image.
relative dispersion -> dispersive power
A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the material's index of refraction at the three chief Fraunhofer lines in the...
relative intensity noise
The inherent laser amplitude noise relative to the average optical power produced by the laser; the RIN decreases rapidly as current is increased.
remote sensing
Remote sensing is a method of data collection and observation where information about objects, areas, or phenomena on Earth's surface is gathered from a distance, typically using sensors onboard...
repressing -> molded blank
A blank whose basic surface curves are attained by heating and forming a given weight of raw glass; a rough glass blank resembling the finished lens in size and shape. After molding, a precision lens...
residual absorption and scattering
Loss mechanisms that degrade the performance of all thin-film optical devices by removing radiant flux out of the specular beams.
residual blue
The optical phenomenon in which white light dispersed by small particles in suspension appears blue when viewed through a suitable Nicol prism.
residual gas analysis
A measurement in optical thin-film coating processes whereby the gases remaining in the vacuum chamber after coating are characterized by mass spectroscopy.
resistance heater
A crucible made of electrically resistive material through which a current is passed to heat the material inside, which then evaporates and is deposited as a thin film on a substrate. Resistance...
resistor
A device having electrical resistance and used in an electric current for purposes of protection, operation or control of current.
resistor trimming -> laser resistor trimming
In hybrid or monolithic integrated circuits, the laser ablation of a portion of resistor material to achieve the design resistance value of the circuit.
responsive element -> active element
Component that is externally controlled via electronic or photon signal.
responsive quantum efficiency
The number of electrons emitted per photon incident upon a photodetector.
responsivity
The gain that occurs between light intensity incident on a CCD given by the photocurrent produced.
reversion prism
A prism made of two elements cemented together that, depending on its orientation, inverts or reverts an image. It may be used in converging or diverging light. Sometimes referred to as a K prism.
rotational transition
One of the types of change in the energy levels of molecules or atoms in a laser that can result in lasing action. Because the energy levels between rotational states are small, such lasing action is...
R
resistance; roentgen; Rankine
Rabi oscillations
Rabi oscillations are a fundamental phenomenon in quantum mechanics that describe the periodic and reversible exchange of energy between two quantum states when subjected to an oscillating external...
radargrammetry
The analysis of the photographs taken from the radar display of a survey aircraft and used when recording terrain that is obscured by clouds.
radiac
An acronym for radioactive detection, identification and computation. The term refers to the detection and measurement of the intensity of emitted nuclear radiation.
radial distortion
An alteration in magnification from the center of the field to any point in the field, measured in a radial direction from the center of the field. Some radial distortion is inherent in most optical...
radial distribution method
A statistical analysis of facts obtained when the intensity of x-ray diffraction is calculated at different angles. In this way, the interatomic distances of gases and liquids can be deduced, with...
radial velocity
The velocity from object to observer, directed along the line of sight.
radially variable reflectivity optic
A reflecting optic whose reflectivity is a function of the radial distance from the optic axis; can be used to convert a Gaussian beam to one of uniform cross section.
radiant exposure -> exposure
In optics, the total radiant energy incident on a surface-per-unit area. It is equal to the integral over time of the radiant flux density. Also known as radiant exposure.
radiant heat
Infrared radiation emitted from a source that is not heated sufficiently to give off visible radiation.
radiation
The emission and/or propagation of energy through space or through a medium in the form of either waves or corpuscular emission.
radiation pattern
Relative power distribution as a function of position or angle.
radiation pyrometer
Also known as radiation thermometer. A pyrometer in which the radiant intensity from the source to be measured is used to calculate its temperature. The usual detector is a thermocouple, thermopile...
radiation trapping
That process by which radiation spontaneously emitted by a volume of optical materials is resonantly reabsorbed within the same volume before it escapes. This effect is manifested in a reduction in...
radiation-monitoring film
The film used in photographic dosimetry to record the types and amounts of ionizing radiation, such as x-rays and gamma rays, present in an area for a set interval of time. The negative produced by...
radiation-shielding windows
Plates of glass containing as many heavy metal oxides as can be dissolved in the glass without causing devitrification. The glass is yellow, very heavy and has a high refractive index. It is almost...
radiative recombination -> band-to-band photoluminescence
The emission of a photon by the return of an excited carrier from the conduction band to the valence band of a semiconductor along a radiative recombination path. The resulting photoluminescence...
radio astronomy
The detection and analysis of naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum.
radio frequency
The frequency range for radio and television transmission.
radio telescope
An instrument designed to collect naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum in amounts sufficient to be measured.
radiograph
An x-ray or radium photograph illustrating the nonuniform density of the structure that the rays penetrate.
radiographic amplifier screen
A solid-state panel of the photoconductor-electroluminescent type. The photoconductive layer, sensitive to x-rays, is coated by the electroluminescent, which gives the visible image. When the former...
radiography
A photographic process using x-ray radiation or the g-rays of radioactive materials.
radiometallography
The analysis, by x-rays, of the crystalline structure and other properties of metals and alloys.
radiometer
A device used to measure the intensity of radiant energy.
radiophotography
The transmission of photographic images or pictures by radio waves.
radix
Total number of characters available to each position of a digital numeric system.
RAE
resistive anode encoder
rail -> optical bench
A support for optical parts comprising a solid bed that permits precise longitudinal movement of one component relative to the others, and a number of sliders equipped with holders for lenses, lamps,...

Photonics DictionaryR


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