Photonics Dictionary

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...

A digital imaging method whereby the first gray level in the ordered sequence and the position of the first lengths of all runs are specified; used when there are only two possible gray levels...

A digital imaging method whereby the first gray level of each sequential point-by-point sample and its position in the succession of gray levels is encoded. It is used when there is a tendency for...

A term describing a type of scratch.

In a linear stage, any deviation from the desired translation across a flat, straight line.

A ruticon is an opto-electronic device in which light going through it can be modulated by an electric field. The intensity distribution of the resulting image can be precisely controlled....

The term "Rydberg atom" refers to an atom in a highly excited state where one or more of its electrons are in a Rydberg orbital. A Rydberg atom is characterized by having an electron orbit that is...

The reversal of a developed image due to the exposure of the partially developed image to actinic light.

The movement of the eye as it focuses on details of a scene. Some imaging systems mimic this movement by small, rapid scanning motions of the sensor.

A special-purpose polarimeter having a scale calibrated directly in the concentration of sugar in the test solution.

A term used to describe a saddle-shaped -- i.e., convex along one axis, concave along the other -- polished surface, generally an error, whose contours are apparent by the shape of Newton's rings.

Filtered light to which photographic or other photosensitive materials are not responsive; used to illuminate darkrooms when film is being processed. The color of the filter varies according to the...

1. In the geometric sense, an abbreviation for the term "sagitta,'' the height of a curve measured from the chord. and it is exact for a parabola. 2. Conforming a sheet of glass to a...

The shape of the edge of a concave surface when the depth of the bevel plane to the vertex of the surface is controlled to a required distance.

Sagnac interferometry is a technique used to measure rotation or angular velocity based on the principle of interference. It relies on the Sagnac effect, named after the French physicist Georges...

Formula that describes the thermal equilibrium of gas electrons and ions as a direct function of variations in temperature.

On a chromaticity diagram, the point that denotes the chromaticity sample.

A device that acquires a signal and then stores it for a specified period of time before processing, and used, for example, to reduce noise as in correlated double sampling.

A crude area on the polished surface, produced during coarse grinding, that subsequent fine grinding does not remove, owing, to some extent, to coarse grains of grinding sand that mixed with finer...

The simultaneous exposure of two holographic plates with emulsions facing the object. After deformation, a second pair of plates is exposed to the deformed object. The back plate of the initial pair...

Sapphire crystal refers to a transparent, single-crystal form of aluminum oxide (Al2O3) known as corundum. It is one of the hardest known materials, second only to diamond on the Mohs scale of...

Sapphire optical fiber is a type of optical fiber made from single-crystal sapphire, which is a form of aluminum oxide (Al2O3) that is highly transparent in the infrared region of the electromagnetic...

A sapphire window refers to a transparent optical component made from sapphire crystal. Sapphire is a single-crystal form of aluminum oxide (Al2O3) that is highly prized for its exceptional optical...

Sapphire refers to a crystalline form of aluminum oxide (Al2O3) that is used in various optical and photonic applications due to its exceptional optical, mechanical, and thermal properties. Sapphire...

A direct-readout television pickup tube.

A saturable absorber is a type of optical device that exhibits variable absorption properties depending on the intensity of incident light. In essence, it becomes less absorbent as the light...

A double-plate device used to transmit polarized light and form interference fringes of the light, thus indicating its presence. It consists of two calcite plates of equal thickness, cut parallel to...