Photonics Dictionary: C

A photoconductive cell having cadmium sulfide as its photoconducting material for the production of a very high dark-light resistance ratio.

SI unit of luminous intensity. It is defined as one sixtieth the normal intensity of one square centimeter of a blackbody at the solidification temperature of platinum. A point source of one candela...

Envelopes for cathode-ray tubes are made by blowing glass in the same manner as light bulbs. They have a fairly flat end face to carry the phosphor material applied internally.

1. A single unit in a device for changing radiant energy to electrical energy or for controlling current flow in a circuit. 2. A single unit in a device whose resistance varies with radiant energy....

A photoemissive detector sensitive to wavelengths up to 1 µm. It has one sharp maximum of sensitivity at 350 nm and a broad maximum at 800 nm.

The number of channels per unit bandwidth handled by a single optical fiber.

A photoelectric detector consisting of a glass tube internally coated with a low conductance material. Voltage applied along the tube causes photoemission from the photocathode at the end of the tube...

The parallel resistance and capacitance appearing between the active guard ring junctions in a silicon photodiode.

The creation of a diode laser structure by liquid-phase epitaxy over a grooved substrate.

A laser having a rare-earth chelate within a plastic host as the lasing material. The chelate laser is easily pumped and has a high quantum efficiency and narrow emission lines.

Any of several compounds capable of binding heavy-metal ions, thereby preventing interaction between the bound ions and the rest of the medium.

A television system that does not broadcast television signals but transmits them over a closed circuit.

A plane mirror mounted on a polar axis that lies parallel to the plane of the mirror. When the mirror is rotated once in 48 hours, celestial objects can be made to appear stationary and are...

That part of an infrared detector-Dewar assembly that limits the solid angle viewed by the sensor; it is maintained at a uniformly cold temperature so that no thermal energy is emitted. Also known as...

A ring dye laser that uses prisms and a saturable absorber within the laser cavity to shape and shorten the pulses generated. Counterpropagating modes oscillating simultaneously in the ring...

A television system that is capable of producing an image whose colors approximate the colors of the original, by the use of additive color mixing of the three primary colors.

A laser warning and countermeasure system containing a sensor that indicates the direction of a laser beam, and analytical instruments to determine pulse code, repetition frequency and wavelength.

Also called complementary dominant wavelength. On a chromaticity diagram, the wavelength on the spectrum locus that lies on the same straight line as the achromatic point and the sample point for a...

A type of laser welding of thin materials using a defocused or low-power carbon dioxide laser beam. The energy is absorbed by the material through conduction and melts the material to produce an edge...

Method of disk rotation used for optical disk drives, in which the spindle motor decreases the speed of the disk's rotation as the head moves from the inner tracks to the outer, so that the radial...

The group of adjacent pixels on which the convolution process is carried out.

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 prism formed by dividing a Nicol prism in a plane parallel to the path of vibration of the transmitted light and taking out the wedge-shaped piece. After the pieces are rejoined, the planes of...

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...

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,...

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

A signal-averaging technique that improves signal-to-noise ratio by comparing a sampled signal with a reference signal bearing some known relation to the received signal.

The electrostatic field acting locally within a crystal as a result of the microscopic arrangement of atoms and ions in the lattice.

A bevel produced by grinding with a cup-shaped tool.

A lens aberration that causes a flat object surface to be imaged onto a curved surface rather than a plane.

1. In detector technology, the long wavelength at which detector response falls to a set percentage (usually 20 or 50 percent). 2. In fiber optics, the shortest wavelength at which a fiber transmits...

In filter terminology, that wavelength where the filter transmission increases beyond 5 percent.

Light produced when a metal is bombarded with high-velocity electrons causing small amounts of the metal to vaporize and emit radiation. Also known as electronoluminescence.

1. Attribute of a visual sensation that permits a judgment to be made of the amount of pure chromatic color present. 2. The portion of a composite video signal that carries the chrominance values,...

1. An eyepiece or magnifier with a scale at its image plane. That scale is placed in contact with an object, permitting direct measurement of its size. 2. Also called traveling stage and traveling...

A set of mirrors along a telescope's polar axis designed to redirect light to a fixed position without being affected by the motion or position of the telescope. From the French word for "elbow."

A standard lens interface initially made for 16mm movie cameras and now used primarily on closed-circuit television cameras. It is a 1-in.-diameter, 32-thread-per-inch interface with a...

The three lines in the spectrum of cadmium that have the purest radiations and that were first used by Michelson to calculate the standard meter.

An inorganic compound, yellow to orange in color, that fluoresces strongly enough when bombarded by a high-current-density electron beam to be used as a high-intensity light source.

A calcium indicator is a molecule that is sensitive to changes in calcium ion (Ca2+) concentrations in biological systems. These indicators are commonly used in various fields, including cell...

An optical wedge in which transmittance or density is a function of the location of the wedge, relative to a specific optical system.