Photonics Dictionary: R

In a gas, the temporary drop in density caused by contact with a sound wave.

The pattern of lines traced by rectilinear scanning in display systems.

In imaging technology, a device that converts raster or line-scan data to pixel form for further processing.

A display in which regeneration takes place serially at a fixed speed in a set pattern through the scan lines.

The vertical or horizontal distance between two addressable points on a display screen; indicates the basic resolution element of a terminal.

An electronic device that minimizes short-term drift effects and random measurement error inherent in alternate ellipsometric measurement of two signals.

Ratiometry is a technique used in various scientific fields, particularly in analytical chemistry and biochemistry, to measure concentrations or quantities by comparing the intensity of two different...

A term that describes any state of glass before its manufacture as an element.

A geometric representation of a light path through an optical device; a line normal to the wavefront indicating the direction of radiant energy flow.

A graph of the intersections of a fan of rays with the final image plane, plotted as a function of the positions of the rays in the pupil of the system.

Ray tracing is a rendering technique used in computer graphics to simulate the way light interacts with objects in a scene. It involves tracing the path of rays of light as they travel through a...

When a lens system with a circular aperture is free of aberrations, the image of a point object will appear as a disc of finite size surrounded by concentric rings. When two points are separated such...

A device that is used to determine the index of refraction of a gas or liquid through the interference patterns formed by two beams of light, one of which has been transmitted by the sample. A single...

The restriction of wavefront error to within a quarter of a wavelength of a true spherical surface to assure essentially perfect image quality.

That element of a spectrum line in scattered radiation having a frequency equal to that of the corresponding incident radiation, due to ordinary or Rayleigh scattering.

A prism system designed to produce a very high dispersion of light.

In the region of a Gaussian beam focus by a diffraction-limited lens, it is the axial distance from the point of minimum beam waist (Wo) to the point where the beam diameter has increased to .

Rayleigh scattering is a phenomenon that occurs when light waves interact with particles or molecules that are much smaller than the wavelength of the light. It is named after the British scientist...

Reactive evaporation refers to a process in thin-film deposition where a material is deposited onto a substrate through evaporation, and chemical reactions take place during or after the evaporation...

In chemistry, a device in which a chemical reaction takes place. In electronics, a device that introduces reactance into a circuit.

The transparent component of an optical reader that transmits the image rays of the characters to be read.

An optical storage product that can be used for playback only.

In an optical data storage system, denoting the optical head's ability both to record information and to detect it for playback.

That part of a magnetic or optical tape or disc drive that retrieves data from or records data on the recording media.

A low-power magnifier that usually has a large diameter.

A reagent is a substance or compound that is used in a chemical reaction to bring about a specific transformation or to detect the presence or absence of another substance. Reagents are employed in...

An image that is formed when rays emerging from an optical system all converge to a point on the optical axis. A real image can be seen on a screen in the image space of the given optical system.

The ability of a vision system to interpret an image in a short enough time to keep pace with most operations.

A nonhomogeneity of index in flat glass that is in the form of an approximately plane layer.

A photodetector mounted in the same package as a laser diode that is positioned to monitor the output from the rear facet of the diode.

A type of internal focusing in which only the lens elements closest to the rear of the lens barrel are moved.

The restricting opening at the rear of a lens or prism that is commonly defined as the maximum diameter of the emergent cone for the specified field of view, at infinity focus.

Also known as display primaries. Colors formed by a television receiver that are of constant chromaticity and variable luminance, and that, mixed in certain proportions, form other colors. Red, green...

A detector and signal demodulator used in optical communications systems to receive a signal and often to translate it into an electronic signal.

The fundamental wavelength standard of time or frequency. An atomic standard, it is properly expressed as 9,192,631,770 times the frequency of the transition between the hyperfine structure levels of...