Photonics Dictionary: R

A radioactive element that is placed or injected into a system to obtain an autoradiogram of the system. It is used in a number of fields where standard methods of internal imaging, for example,...

An instrument used to detect radioactive materials: alpha particles or helium nuclei; beta particles or free electrons; and gamma rays, which are x-rays of very short wavelength. They may be detected...

The photographic image of a thin specimen having a radioactive isotope that, formed through contact between the specimen and a photographic plate, displays the distribution of the radioactive...

The thin, transparent film made up of specific substances applied to glass-air surfaces for the purpose of decreasing the amount of reflected light.

Thin-film coating, single or multilayer, that is applied to a substrate to increase its reflectance over a specified range of wavelengths. Metal film, transparent or opaque, is the oldest form of...

A reconfigurable optical add-drop multiplexer (ROADM) is a key component in wavelength-division multiplexing (WDM) optical communication networks. It allows for flexible and dynamic routing of...

An acronym for radioactive detection, identification and computation. The term refers to the detection and measurement of the intensity of emitted nuclear radiation.

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...

A photographic process using x-ray radiation or the g-rays of radioactive materials.

The study of radioactive substances and high-energy radiations such as x-rays and g-rays.

Luminescence produced by the bombardment of radiant energy such as x-rays, radioactive waves or alpha particles.

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...

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...

Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that allows for high-resolution, in vivo imaging of biological tissues at the cellular level. It is particularly useful in...

The term reflective is an adjective that describes the ability of a surface or material to reflect light or other forms of radiation. It implies the capability of bouncing back or redirecting...

A lamp used in projection that is made with a reflector built into the bulb, normally by coating a portion of its interior with a reflective material to ensure the reflector's optimum position in...

Remote inspection refers to the process of inspecting, evaluating, or monitoring assets, equipment, infrastructure, or systems from a distance, typically using remote sensing technologies and...

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...

A measurement in optical thin-film coating processes whereby the gases remaining in the vacuum chamber after coating are characterized by mass spectroscopy.

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 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 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...

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...

A form of binary notation that includes a third code representing a stop between bits.

An interferometric method for describing the surface shape of large coated or uncoated optical flats. The procedure uses a commercially available small-aperture phase-shifting interferometer for...

Robotic arms, also known as robot arms or manipulator arms, are mechanical devices designed to mimic and perform the functions of human arms. They consist of multiple articulated segments, joints,...

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...

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...

A term used to describe a very coarse grinding process.

A Rugate filter is a type of optical filter that is designed to have a continuously varying refractive index profile throughout its thickness, rather than the discrete layers found in traditional...