Photonics Dictionary: R

Clear All Filters x glasses x R x
radiation-shielding windows

Plates of glass containing as many heavy metal oxides as can be dissolved in the glass without causing devitrification. The glass is yellow, very heavy and has a high refractive index. It is almost...

rail -> optical bench

A support for optical parts comprising a solid bed that permits precise longitudinal movement of one component relative to the others, and a number of sliders equipped with holders for lenses, lamps,...

rare-earth doped fiber

An optical fiber in which ions of a rare-earth element, such as neodymium, erbium or holmium, have been incorporated into the glass core matrix, yielding high absorption with low loss in the visible...

rare-earth type glass

Optical glasses containing the oxides of rare earths such as lanthanum to impart a very high refractive index combined with a low dispersive power.

raw glass

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

reading glass

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

ream

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

reflection reduction coating

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

refracted ray

A light ray that has had its direction altered because of its traversing an air-to-glass interface at some angle. In an optical waveguide, a ray that is refracted from the core into the cladding.

relative dispersion -> dispersive power

A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the material's index of refraction at the three chief Fraunhofer lines in the...

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...

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 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

resolution test chart -> resolution target

resolving power chart -> resolution target

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...

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...

Photonics DictionaryR

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