Photonics Dictionary: D

Description of a material, such as a water-soluble salt, that will continue absorbing moisture from the surrounding atmosphere until it dissolves into a liquid.

The term delta error (delta-E) generally refers to the difference or change in error between two values or states. The word "delta" is often used in mathematics and science to represent a change or...

A compact, folded version of a Dove prism, made of high-index glass with a silvered base and used for image rotation.

Separating two or more signals that have been combined into one signal.

1. An instrument used to measure the opacity or density of dyes, pigments or dispersed particles that form an image in or on a medium, such as a photographic film. 2. A device used to measure the...

The detection and analysis of the transmission and reflection properties of objects and photographic images.

The exact mathematical description of the interactions of matter and intense electromagnetic fields, such as those that occur when laser sources are used to excite flame gases for spectroscopic...

The region at the PN junction in a semiconductor radiation detector where the potential energies of the two materials create an energy barrier, which results in an electrical field that depletes the...

A device that obliterates the polarization of a polarized beam by reflecting the beam in all directions at right angles to its axis.

A critical image parameter in applications where object position may change dynamically relative to the imager; this is a sensitive function of the system's preclosed loop (initial) focal range and...

The distance, on either side of the object plane focused on, through which satisfactory image definition can be obtained. For the special case of an imaging system with lens axis perpindicular to the...

The range of image distances that corresponds to the range of object distances covered by the depth of field.

The direct appreciation of the distance between a given object and the observer, or between the front and back of a solid object. Real depth perception is achieved by the retinal disparity formed by...

The ray refracted by a sphere of transparent material that travels back as closely as possible to the original path formed by the incident ray.

Design and engineering consulting services refer to professional services provided by specialized firms or individuals to assist clients in various aspects of product development, system design, or...

A diagram in which the variable frequencies of a spectral band system are plotted corresponding to ascending values of the quantum numbers of the upper and lower energy levels.

Observed electroluminescence of zinc sulfide phosphors when excited by an electric field. This effect is the basis for the alternating-current phosphor panel technology.

The interaction of superimposed light from two separate sources that results in a combined intensity that is less than the sum of their individual intensities before they were superimposed.

The square of the ratio of the measured detectivity to the theoretical maximum detectivity.

A measure of the sensitivity of a detector; the reciprocal of noise equivalent power (NEP). See D*.

1. A device designed to convert the energy of incident radiation into another form for the determination of the presence of the radiation. The device may function by electrical, photographic or...

A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format. Each element within the array is capable of detecting electromagnetic...

In optical communication systems, operations in which the amplitude of the pulses, as opposed to their width, determines the distance between repeaters.

A detector-Dewar assembly typically refers to a combination of a detector and a Dewar flask used in scientific instruments, particularly in the field of infrared spectroscopy or other applications...

A device in which the functions of optical detector and emitter are combined.

A type of pyroelectric detector with favorable qualities of linearity, sensitivity and spectral responsivity used in FTIR detectors.

A discharge lamp filled with deuterium to produce high-intensity ultraviolet radiation for use in spectroscopic analysis.

A chemical solution that changes the silver salts (latent image) of exposed photographic film into black metallic silver (visual image).

The process by which a vitreous or amorphous substance forms a crystal structure at a specified temperature.

An evacuated, double-walled container for storing liquids at low temperatures. Often made of glass, the vessel resembles a Thermos bottle.

Dewetting is a phenomenon in materials science and physics where a thin film or coating spontaneously undergoes a process of breaking up and forming isolated droplets on a substrate. This occurs due...

Able to rotate the plane of polarization of a transmitted, plane-polarized light beam clockwise as seen by a viewer looking in the same direction as the traveling light. Also called dextrorotary; the...

A caustic formed by refraction.

An airspaced achromatic doublet telescope objective.