Photonics Dictionary: C

A powerful and flexible machine-learning approach that can be used in machine vision to help solve difficult problems. Inspired by biological processes, multiple layers of neurons process portions of...

A telephoto lens form noted for its lack of distortion.

The simplest lens in which all primary aberrations may be corrected. It consists of two positive crown elements on either side of, and spaced away from, a negative flint element.

The coupled pairs of electrons that carry supercurrents through the body of a superconductor, relative to a coherent macroscopic wave function with the superconductor.

An instrument used to measure the coordinates of a point on an object such as a photographic plate.

An early type of nonvacuum photocell consisting of a layer of copper oxide on a metallic substrate, with a thin transparent layer of a conductor over the oxide. When light falls on the cell, a small...

A corner cube, also known as a corner reflector or retroreflector prism, is a type of optical device used to reflect light or electromagnetic waves back towards their source with minimal deviation in...

A compound prism formed by cementing together two 30° prisms, one of right-handed and one of left-handed quartz. It has good ultraviolet-transmitting qualities and no double refraction.

Solar regions characterized by low density and open magnetic fields where high-speed solar wind streams originate. Originally believed to be "M'' regions, coronal holes are the precursors of the...

In rangefinders and height finders, a rotatable or sliding wedge-shaped element used to divert the line of sight precisely to correct errors in the optical system.

An optical wedge of very small angles that admits light while sealing out moisture and dirt and that may be rotated to compensate for the errors in the entire system. Correction windows are sometimes...

Temperature of the blackbody having chromaticity nearest to that of the test source on a specified chromaticity diagram.

A technique for removing thermal noise and drift from focal plane assemblies by sampling the system output between views of scene elements and then subtracting the resulting value from the subsequent...

Bohr's formulation that every new theoretical principle must correspond to the salient classical predecessor. The principle imposes mathematical limits on theoretical discovery and implies, for...

A formula indicating that, for an imaging lens system, the image brightness for off-axis points will fall off at a rate proportional to the cos4 of the off-axis field angle.

Law relating the illuminance (or irradiance) of a surface to the cosine of the angle, q, between the normal to the surface and the direction of the incident wave.

The ongoing expansion of the universe based on observations of the recession of distant galaxies from each other as evidenced by the redshift in their spectral lines.

A system consisting of two or more Geiger-Müller counters, connected in coincidence with their centers on an axis. The only particles recorded are those traversing all counters, near the axis,...

The scattering of charged particles, moving through matter, by the electrostatic force exerted by other charged particles.

1. In color development, the chemical that combines with certain by-products of the development procedure to form a dye. 2. Device for distributing optical power among two or more ports. 3. Device...

A technique used in integrated optics where a groove is cut on a substrate surface and covered by a thin film to facilitate the construction of filters, resonators, beamsplitters and grating couplers...

A coverslip, also known as a cover glass or cover slip, is a thin and flat piece of transparent material typically made of glass or plastic. It is used in microscopy to cover a specimen mounted on a...

Observed when alterations in the luminous sterance at the contour of an object create the illusion of the outer zones appearing darker than the inner regions, despite the consistent luminance of the...

The deformation of a material at high levels of stress, often associated with elevated temperatures.

Cresyl violet, also known as cresyl violet acetate or cresyl echt violet, is a synthetic organic compound belonging to the class of triarylmethane dyes. It is commonly used in histology and...

A crimped metal cylinder that holds the connector to the cable through the cable's strength member.

That wavelength at which the absorption of a given element or system begins to demonstrate an inconstant value.

The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is...

In an optical system, the aperture size at which the lens gives its best overall performance.

Relative to a light source, the frequency at which the source appears to fluctuate in light intensity half the time and remains constant during the other half.

The fusion frequency of flicker that is needed just to produce complete fusion and to assure the visual sensation of continuous illumination measured in cycles per second.

Illumination in which the light source is imaged at the object.

Intense scattering in the region of the liquid-gas critical point. At this point the gas will strongly scatter all light to create a vivid opalescent appearance.

Recombination of only the light that is correctly dispersed by the first stage of a polychromator through its wide intermediate slit (common during Thomson scattering experimentation), which is...

Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects in the field of view. They were formerly made from a single strand of...

1. A defect inherent in a multiple-axis positioning system whereby an adjustment of one axis causes an undesired change in another; its severity depends upon the degree to which the positioning axes...

The positioning of two Nicol prisms so that their axes are at right angles to each other. With this arrangement, light transmitted by one prism will not be transmitted by the other.

The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).

The spectrographic analysis of matter that is in a cooled state. Generally, a mechanical refrigerator is used to lower the temperature of the sample, allowing isolation and study of the sample and...