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189 terms

Photonics Dictionary: D

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diode laser -> diode laser

A diode laser is a type of laser that uses a semiconductor diode as the active medium to generate coherent light. Semiconductor diodes are electronic devices that conduct electricity primarily in one...

diode laser

diode-pumped solid-state laser

A diode-pumped solid-state laser (DPSSL) is a type of laser system that uses semiconductor diode lasers to pump energy into a solid gain medium, resulting in the generation of coherent light. This...

dioptrics

The branch of optics that deals with the study of the refraction of light, particularly by the transmitting medium of the eye, and by lenses.

diplexer

A coupling unit that enables more than one transmitter to operate at the same time or separately on the same antenna.

direct detection

In a fiber optic transmission system, the conversion of received optical pulses directly to an electrical signal.

direct illumination

Light produced by visible radiation that moves from the light source to the object without reflection. With respect to microscopy, this is the light that directly strikes the stage of the microscope...

direct laser interference patterning

Also called DLIP, a high-speed, high-resolution processing technique that uses high-power, pulsed laser systems to directly ablate micro- and nanoperiodic structures with different features on large...

direct scanning

A scanning technique in which the object is illuminated the entire time, and in which picture elements of the object are viewed singly by the television camera.

direct-line fluorescence

With respect to atomic fluorescence spectroscopy, the fluorescence that is emitted by an atom at a spectral line of a wavelength that is longer than that of the stimulating radiation.

direct-view storage tube

A cathode-ray tube in which secondary emission electrons form a display of high intensity.

directed energy

Directed energy refers to a type of energy that is emitted and transferred in a controlled direction. The term is often associated with military and technological applications where energy, typically...

directional reflectance

Reflectance in a specified direction, for a specified direction of incident illumination.

discharge lamp -> electric-discharge lamp

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.

discontinuously reinforced aluminum

A composite derived from aluminum alloy powder and silicon carbide, used as an optical substrate in air- and spacecraft applications. It is as light as aluminum but exhibits greater strength and...

discrimination

The degree to which a vision system is capable of sensing differences in light intensity between two regions.

discriminator

A circuit incorporated into counter systems that records only pulses that have amplitudes between two preselected limits.

dispersing prism

A prism or series of prisms used to disperse a beam of radiant energy of mixed wavelengths into its spectral components.

dispersion

Dispersion refers to the phenomenon where different wavelengths (colors) of light travel at different speeds when passing through a medium. This variation in the speed of light for different colors...

dispersion filter

A complex filter that uses polarization and interference to transmit light that is nearly monochromatic.

dispersion-limited operation

Operation in which the dispersion of a pulse limits the distance between repeaters in optical systems. Waveguide and material dispersion can make recognition of a pulse impossible.

dispersion-shifted fiber

A dispersion-shifted fiber (DSF) refers to a type of optical fiber designed to minimize the effects of chromatic dispersion, which is the phenomenon where different wavelengths of light travel at...

dispersive correlation spectrometer -> mask spectrometer

Instrument that uses absorption spectroscopy to detect gases in planetary atmospheres. Dispersed incoming radiation is transmitted to one or more sampling elements, or masks, before reaching the...

dispersive lens -> diverging lens

A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...

display primaries -> receiver primaries

Also known as display primaries. Colors formed by a television receiver that are of constant chromaticity and variable luminance, and that, mixed in certain proportions, form other colors. Red, green...

dissector

In optical character recognition, the mechanical or electronic transducer used to detect the level of illumination present in the various portions of an illuminated sample region.

dissonance

In optics, the production of maxima and minima by the superimposition of two sets of interference fringes from light of two different wavelengths.

distal end

The end of an optical fiber farthest from the source of illumination.

distance-luminosity relationship

In astronomy, the relation that states that the intensity of a star's visible radiation is inversely proportional to the square of the distance from which it is viewed.

distortion

A general term referring to the situation in which an image is not a true-to-scale reproduction of an object. The term also is used to connote the temporal alteration of the signal's waveform shape....

distortion-limited operation

The limitation on performance imposed by the distortion of a received signal rather than its amplitude or power.

distributed Bragg reflector

A device similar to distributed feedback lasers in construction and operation, but in which the period grating that produces feedback is removed from the gain region to simplify fabrication. The...

distributed feedback laser

A distributed feedback laser (DFB laser) is a type of semiconductor laser diode designed to emit coherent, narrow-bandwidth light with precise control over the wavelength. It achieves this through a...

divergent lens -> diverging lens

diverging lens

divided slit scan

A scanning technique in optical character recognition in which an array of photocells is used to scan each character to determine its horizontal and vertical characteristics.

diffraction-limited; diode logic

DLL

dynamic link library

DMI

direct measuring interferometry

DMP

digital map processor; digital micromirror device

DMS

dynamic scattering

DMTF

diffraction-limited modulation transfer function

doma

A primitive crystal possessing two plane surfaces that form a dihedral angle bisected by another plane surface.

dome -> optical instrument dome

A dome-shaped structure used for some optical instruments in place of a flat window. The transparent material should be of good quality and the hemispherical surfaces should be concentric.

dominant wavelength

A single wavelength of light that matches the color of a given sample when combined in suitable proportions with white light and a suitable adjustment of intensity.

doping

In the context of materials science and semiconductor physics, doping refers to the intentional introduction of impurities into a semiconductor material in order to alter its electrical properties....

Doppler effect

The effect produced on a wave frequency because of the relative motion of a source or an observer. The radiation emitted from a source that moves away from an observer appears to be of lower...

Doppler principle

The theory established by Christian J. Doppler in 1842 that states that the rate of change in distance between a perceiver and a radiation source determines the change in frequencies.

Doppler signal

A signal traveling from transmitter to receiver that has an altered frequency due to the Doppler effect.

Doppler velocimeter -> laser Doppler velocimeter

Device which determines particle velocity through the measurement of scattered interference of a beam pair from a single source. The measured light is Doppler shifted which provides information...

Photonics DictionaryD