Photonics Dictionary: R

An instrument designed to collect naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum in amounts sufficient to be measured.

A gas laser in which the electrodes are mounted perpendicular to the optical resonator.

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...

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

The luminescence displayed when particular minerals are irradiated with β-rays and g-rays, after being exposed to nuclear radiation.

A microscope to which a beamsplitter and illuminated reticle have been added that is used to measure contact lenses.

Raman spectroscopy is a technique used in analytical chemistry and physics to study vibrational, rotational, and other low-frequency modes in a system. Named after the Indian physicist Sir C.V. Raman...

Also known as RAMP microscopy, random access multiphoton microscopy is a microscopic technique that uses multiple acousto-optic modulators to enable faster and addressable scanning of 3D cellular...

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

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...

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

A two-dimensional scanning process, in which a slow sector scan, propagated in one direction, is superimposed at right angles upon a rapid sector scan.

The scanning of a region in a given sequence of slender, straight parallel strips.

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...

A microscope that uses a reflecting objective; often used with ultraviolet or infrared radiation.

A telescope that uses a reflecting objective to focus an image of a distant object at a focal point.

A means of high resolution study through the application of soft and hard x-rays onto a sample surface in order to obtain image information from 1-10 nm layers and surfaces. The x-ray source emission...

Reflectance spectroscopy is a technique used to analyze the reflective properties of materials across various wavelengths of the electromagnetic spectrum. By measuring the reflectance of light from a...

Loss mechanisms that degrade the performance of all thin-film optical devices by removing radiant flux out of the specular beams.

In atomic fluorescence spectroscopy, fluorescence emitted by an atom at a spectral line of a wavelength identical to that of the stimulating radiation.

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.

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...

A small erect-image telescope for use as a sighting device on a rifle. The chief requirement is a long eye relief to avoid damage to the eye due to recoil. The power may lie anywhere between 1 and...

A ring laser gyroscope (RLG) is a type of gyroscope that uses laser light to detect and measure changes in orientation. It operates based on the Sagnac effect, which is a fundamental principle of...

A form of Cassegrain telescope having a concave hyperbolic primary and a convex hyperbolic secondary. This form permits the simultaneous correction of spherical aberration and coma.

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...

The analysis of the photographs taken from the radar display of a survey aircraft and used when recording terrain that is obscured by clouds.

The emission and/or propagation of energy through space or through a medium in the form of either waves or corpuscular emission.

A mode in an optical waveguide whose fields are transversely oscillatory everywhere external to the waveguide. It exists even in the limit of zero wavelength.

A thermocouple that is used in infrared spectroscopy to detect a sample's infrared emittance. See thermocouple.

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...

A very uncommon lamp in which a tungsten electrode is heated to incandescence by a radio-frequency electrical current.

When light is transmitted through matter, part of the light is scattered in random directions. A small part of the scattered light has frequencies removed from the frequency of the incident beam by...

A flexible fiber cable with a small diameter that transports light from the excitation laser to the target. Used in Raman spectroscopy, the probe is capable of obtaining high-quality data at high...

Essentially, noise that cannot be predicted. Therefore, even if the magnitude of sound or oscillation in a system is known at a given moment, random noise can change in a short time.

A double meniscus system in which two achromatized meniscus lenses are arranged symmetrically on either side of the aperture stop, reducing or eliminating distortion, coma and lateral color.

Rare earth dopants refer to elements from the lanthanide series, also known as rare earth elements, that are intentionally introduced into the crystal lattice of a material to modify its properties....

Rare-earth elements (REEs) are a group of seventeen chemical elements found in the Earth's crust, characterized by their unique properties and scarcity relative to other elements. Despite their name,...

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.

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