Definitions

For a lens with an obscured or noncircular aperture, the focal length divided by the effective aperture.

1. That portion of the aperture that functions to collect energy and deliver it to the final system detector. 2. For an obscured or noncircular aperture, the equivalent nonobscured, circular aperture.

In photoelectric sensing, the portion of the transmitted beam that actually functions in the system; the diameter of the beam that determines the presence or absence of an object by being blocked or...

The color of an object when it is illuminated by a nonisophotic source.

A characterization of the throughput performance of data storage systems; the EDR is the total of data retrieved divided by the total time it takes to retrieve it, expressed as megabytes per second.

The real numerical aperture (NA) of a fiber when the computed NA is not valid because of change in the glass indices during drawing and fusion.

As applied to a device or machine, the ratio of total power input to the usable power output of the device.

A weight reducing method whereby material from the rear of a reflector is removed leaving a pattern of ribs normal to the surface in an egg-crate pattern.

A scale attached to a microscope eyepiece that is seen superimposed on the image and that is used to measure the dimensions of the viewed object.

A unit of energy equal to the amount of energy absorbed by one molecule of material undergoing a photochemical reaction, as determined by the Stark-Einstein law.

Three proportional coefficients labeled Am, Bmn, and Bnm, that respectively characterize the rate of spontaneous emission, induced emission, and absorption of radiation by an atom, ion or molecule.

A shift in the direction of the red in the spectral lines of light which, defined by the relativity theory, will have decreased frequencies upon emerging from a highly gravitational field.

Scattering caused by the interaction between ingoing and outgoing particles of the same type, with no loss of kinetic energy.

A change in the refractive index of an optical fiber caused by variation in the length of the fiber core in response to mechanical stress.

Any material of a macromolecular nature that can stretch at room temperature to more than twice its length and return to approximately its original shape when stress is released.

The organic inclusion in quartz crystal that forms delicate films and microspheres and that shows a maximum absorption at 450 nm.

A refracting telescope that uses a prism to bend the line of sight 90°.

An electrically excited laser having carbon monoxide as the lasing material and in which lasing occurs in a partial inversion between adjacent, vibrational fields. Vibrational energy is cycled...

The use of a krypton laser system for the measurement of small molecules aligned by an electric field, by analyzing the absorption of linearly polarized light.

Any lamp whose emission of radiant energy is dependent upon the passage of an electrical current through the emissive medium.

A device that uses four electrodes set in an alternating positive-negative polarity series to focus the beams of charged particles employed in electron microscopes and particle accelerators.

The electric field associated with an electromagnetic wave and thus with a lightwave. The electric vector specifies the direction and amplitude of this electric field.

A lamp that uses the transmission of an electric current through a gas or vapor to produce illumination. Neon, mercury and argon lamps are examples of electric-discharge lamps.

Expression of the length of a transmission medium in terms of wavelengths of the propagating wavelength. In general, electrical length is an expression of physical length in wavelengths, radians or...

The effect whereby a light beam is deflected by a birefringent prism when its polarization is changed by voltage applied to an electro-optical crystal through which the beam passes. The deflection of...

An electro-optic deflector is a device that can change the direction of light beams using an electric field. It operates based on the electro-optic effect, which involves the modulation of the...

A device that detects radiation by utilizing the influence of light in forming an electrical signal. It may be a phototube; a photoconductive, photovoltaic or photojunction cell; a phototransistor;...

The change in the refractive index of a material under the influence of an electrical field.

The spectroscopic analysis of interference patterns using an electronic imaging tube with a Fabry-Perot interferometer to record the fringes.

A material having refractive indices that can be altered by an applied electric field.

An electro-optic modulator (EOM) is a device used to modulate the amplitude, phase, or polarization of light waves using an external electrical signal. Electro-optic modulation is a fundamental...

A radar system that uses electro-optic rather than microwave instrumentation and methods to perform its acquisition and tracking functions.

A device used to control or block a light beam by means of the Kerr electro-optical effect.

A transistor designed to respond to either light or electrical signals.

1. The branch of physics that deals with the use of electrical energy to create or manipulate light waves, generally by changing the refractive index of a light-propagating material; 2....

A type of optical modulator with potential application in optical switching and displays, in which applied voltage causes a change of interfacial tension between mercury and an electrolyte, varying...

The study of the reversible conversion of chemical energy into electrical energy. Electroplating is an electrochemical process.

Type of solid-state display tube in which the readout surface is coated with a material that changes color when positively or negatively charged.

A device consisting of an airtight quartz tube that holds the material to be analyzed. When a high-frequency electrostatic field, generated by microwaves, is applied to the tube, it emits energy of a...

The study of the generation of electromagnetic power by radiation from high-energy beams.

An electrochemical process of metal fabrication using an electrolyte, an anode to supply the metal, and a control of the electrical current and of the deposit of metal on the matrix of a reflector.

A technology that uses electrically activated holograms stored within specially developed crystals to route information in the form of lightwave signals from one optical fiber to another within and...

The deposition of a metallic coating, usually nickel, on a component by chemical means rather than by electroplating; the component is immersed in a solution containing a reducing agent.

The nonthermal conversion of electrical energy into light in a liquid or solid substance. The photon emission resulting from electron-hole recombination in a PN junction is one example. This is the...

The utilization of the light produced when electrical energy is directly converted into light within devices used for visual readout displays or as complex logic-circuit elements. With EL lighting,...

A panel of photoconductive and electroluminescent layers used as either a positive or negative image intensifier, depending on amplitude and phase of its two power supply voltages. The...