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Photonics Dictionary: R

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replicated optics
Optical components, usually reflectors, produced using proprietary techniques that transfer the precision of a master to a number of elements.
representative fraction
Ratio between map or photo linear distance and the actual ground dimensions represented.
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.
resolution
1. In optics, the ability of a lens system to reproduce the points, lines and surfaces in an object as separate entities in the image. 2. The minimum adjustment increment effectively achievable by a...
resolution chart -> resolution target
A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the limiting number of lines per millimeter that an optical system is capable of...
resolution target
A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the limiting number of lines per millimeter that an optical system is capable of...
resolution test chart -> resolution target
A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the limiting number of lines per millimeter that an optical system is capable of...
resolving power
A measure of an optical system's ability to produce an image which separates two points or parallel lines on the object. See Rayleigh criterion of resolving power.
resolving power chart -> resolution target
A chart on paper or glass containing a series of sets of lines at progressively smaller spacing and used to ascertain the limiting number of lines per millimeter that an optical system is capable of...
resonance
Resonance can be defined in various contexts, including physics, chemistry, and music. Here are definitions for resonance in a few different fields: Physics: In physics, resonance refers to the...
resonance absorption (light)
The re-emission of absorbed energy, having the same wavelength as the incident energy, in an arbitrary direction from a particle because of an energy level transition within the material.
resonance fluorescence
In atomic fluorescence spectroscopy, fluorescence emitted by an atom at a spectral line of a wavelength identical to that of the stimulating radiation.
resonance ionization spectroscopy
A type of ultrasensitive laser spectroscopy that can detect quantities as small as a single atom of some substances and that can differentiate between isobars of different elements.
resonance radiation
That radiation emitted by an atom or molecule that has the same frequency as that of an incident particle; e.g., a photon. It generally involves a transition to the lowest energy level of the atom or...
resonance spectrum
The fluorescent emission spectrum emitted by certain substances following the irradiation of one of these substances with light that is of the same wavelengths as its fluorescence.
resonant cavity -> resonator
A resonator is a device or system that exhibits resonance, which is a phenomenon that occurs when an external force or stimulus is applied at a specific frequency, causing the system to oscillate...
resonator
A resonator is a device or system that exhibits resonance, which is a phenomenon that occurs when an external force or stimulus is applied at a specific frequency, causing the system to oscillate...
resorption
The absorption of a material by a medium or system that has formerly been released from absorption by that same medium or system.
responsive element -> active element
In various fields of science and technology, an active element typically refers to a component or substance that actively participates in or facilitates a process, operation, or reaction. Here are...
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.
retardance
The degree of angular shift in the phase of incoming polarized light.
retardation
The phase change of one of the two split beams of an interference microscope.
retardation plate -> wave plate
An optical element having two principal axes, slow and fast, that resolve an incident polarized beam into two mutually perpendicular polarized beams. The emerging beam recombines to form a particular...
retarder cell
A device that uses nematic liquid crystals sandwiched between fused silica substrates to change the phase of polarized light. The cell is tunable from half-wave to zero retardation because variation...
reticle
A reticle, also known as a reticule or graticule, is a pattern or set of markings placed in the focal plane of an optical instrument, such as a microscope, telescope, riflescope, or camera, to...
reticulation
The formation of a distinct, irregular surface pattern on a photographic emulsion due to differential swelling of the gelatin.
retina
The retina is a light-sensitive tissue layer located at the back of the eye, opposite the lens. It plays a crucial role in the process of vision by converting light into neural signals that are sent...
retina camera
A special-purpose camera used by ophthalmologists to photograph the retina of the eye. The optical system operates through the eye pupil, and the illuminant must be able to send light into the eye...
retinal reflectometry
The study of the quality of the image formed on the retina by the measurement of the flux reflected from the eye when the image of a grating or line is produced on the retina.
retinography
The process of photographing the retina of the eye.
retinoscope -> eye test apparatus
Instruments used by ophthalmologists and optometrists to study the eye. There are, for instance, the ophthalmoscope to observe and photograph the retina; the retinoscope and optometer to determine...
retrodirective reflector -> retroreflector
A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their source, regardless of the direction from which the light approaches. Unlike...
retrofocus lens
Also known as reversed telephoto lens. A lens consisting of an ordinary objective with a negative component near its front focal point. Thus, the back focus is large, relative to its focal length....
retroreflecting multipass cell
Two lenses, separated by a distance equal to the sum of their focal lengths, and retroreflecting mirror assemblies, one of which is coaxial with the lenses and the other slightly translated off-axis.
retroreflection
Retroreflection is a phenomenon in optics where light is reflected back toward its source, typically in a direction nearly parallel to the direction from which it originated. This occurs due to the...
retroreflectivity
Retroreflectivity refers to the property of a surface or material to reflect light back to its source, regardless of the angle of incidence. Unlike most surfaces that scatter light in various...
retroreflector
A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their source, regardless of the direction from which the light approaches. Unlike...
return to zero
A form of binary notation that includes a third code representing a stop between bits.
reverse bias
Voltage that produces current flow in the direction of greater resistance to the steady-state direct current; i.e., from the cathode to the anode.
reversed telephoto lens -> retrofocus lens
Also known as reversed telephoto lens. A lens consisting of an ordinary objective with a negative component near its front focal point. Thus, the back focus is large, relative to its focal length....
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.
reverted image
An image whose left side appears to be the right side, and vice versa.
revolving lens fiber optic scanner
A sequential scanning device, utilizing a revolving lens, in which the cathode-ray tube image is transformed into a circle of fibers. The rotating lens focuses each fiber successively on a multiplier...

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