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Photonics Dictionary: R

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Rochon prism
A polarizing prism assembly made up of two cemented calcite halves. The prism transmits the ordinary ray without deviation, while the extraordinary ray is deviated to accomplish the polarization.
Rockwell hardness
Rockwell hardness (Rc) refers to a method for measuring the hardness of a material, primarily metals, using an indentation test. It is named after the Rockwell scale, which was developed by Stanley...
rod
The light-sensitive cells on the retina of the eye that are responsible for low-resolution, peripheral vision.
roentgen
An obsolete term once used to describe a unit of radiation dosage.
roentgenology
The study of x-rays, their biological effects and technology. Named for W.C. Roentgen, who discovered x-rays in 1895.
Rogovsky coil
Conductor element for use in integrated electro-optic systems that measures current flowing through it.
ROI
region of interest
ROID
reconfigurable optical interconnect device
roll
In positioning, rotation about the line of sight or direction of travel.
rolled edge
Also known as a turned-down edge. A rapid change of curvature near the edge in a lens or prism surface.
rolling shutter artifacts
Rolling shutter artifacts are distortions or visual anomalies that can occur in images or videos captured by cameras with rolling shutter sensors. A rolling shutter is a type of image sensor that...
rolloff
A defect in the cleaved end face of an optical fiber in which a portion of the edge has broken away; the complement of lip.
ROM
read-only memory
Ronchi grating
A transparent plate ruled with black lines and equal, clear spaces. It is used as a multiple knife-edge for testing a concave mirror.
Ronchi test
More efficient than the Foucault knife-edge test, this test examines curved mirrors by using a transmission grating with 40 to 200 lines per inch in place of the knife-edge, and a section or slit of...
roof or roof-angle prism -> Amici prism
Also known as roof prism. A type of prism designed by G.B. Amici. It consists of a roof edge produced upon the long reflecting face of a right-angle prism. Used as an erecting system in elbow and...
root mean square
A statistical method of dealing with a series of values where each value is squared, the mean of these squares is calculated, and the square root of that mean is then taken.
root sum square
A statistical method of dealing with a series of values where each value is squared, the sum of these squares is calculated and the square root of that sum is then taken.
Ross lens
A corrective lens system that is placed near the focal plane of a Newtonian telescope to increase its effective field of view by correcting for coma formed by the telescope's paraboloidal mirror.
rotary actuator
A precision positioning device used to produce rotary motion.
rotary camera
A camera system used for microphotography that has a structure, such as a cylinder or surveyor belt, to rotate the documents to be recorded. The image is fixed relative to film motion and exposure is...
rotary laser
A structured light device using a rapidly rotating laser to project a beam of light that appears to the human eye as a continuous circle; used as a reference marker on walls or landscape for...
rotating hologram
A disc composed of a series of holographic optical elements that diffract light at various angles. When spinning, a raster scan may be generated.
rotating mirror scanner
Developed for use in military reconnaissance systems, it consists of a polygonal mirror, drive motor, interface between motor and mirror, and control electronics. Also used in broadband video...
rotating prism camera
A camera, with a rotating prism, that is capable of forming multiple exposures on a constantly moving strip of film.
rotating wedge
A circular optical wedge (prism of small refracting angle) mounted to be rotated in the path of light rays to divert the line of sight to a restricted degree.
rotational power stability
Ability of a laser to resist variations in output power caused when it is slowly rotated about its optical or symmetrical axis.
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...
rouge
A very fine powdered ferric oxide used in polishing lenses.
roughing
A term used to describe a very coarse grinding process.
ROW
resonant optical waveguide
Rowland circle
The circle that contains the slit, grating and primary astigmatic focus of a concave diffraction grating.
Rowland ghosts
In spectroscopy, the false images arranged symmetrically on both sides of the true line and caused by irregularities in the ruling of diffraction gratings.
Rowland mounting
The mounting of a concave diffraction grating and a plate holder at the ends of a rigid bar. The ends follow separate straight tracks that intersect perpendicular to each other. The slit is located...
RPA
rotating polarizer assembly
RPD
radar planning device
rpm
revolutions per minute
rps
revolutions per second
RPT
retroreflective projection technology
RPV
remotely piloted vehicle
RQE
responsive quantum efficiency
RQI
Rayleigh quotient iteration
RR
rapid rectilinear
RSPM
random spatial phase modulator
RSRE
Royal Signals and Radar Establishment
rss
root sum square
RSS
ray surfaces per second; reduced space symbology
RT
real time; remote terminal; room temperature
RTE
radiative transfer equation
RTG
radioactive thermoelectric generator

Photonics DictionaryR

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