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100 terms
Photonics Dictionary: D
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optics x
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diffractive optics
Optical elements that use diffraction to control wavefronts. Diffractive optical elements include diffraction gratings, surface-relief diffractive lenses, holographic optical elements and...
diamond-turned optic
Diamond turning refers to a precision machining process used to produce complex optical components, particularly lenses and mirrors, from materials such as metals, plastics, and crystalline materials...
Dammann grating
A Dammann grating is a type of diffractive optical element (DOE) used to create an array of equally spaced, uniform-intensity spots or beams. It is named after its inventor, Dr. Herbert Dammann. The...
damped least squares
An organizational method used in optical design computer programs. The technique produces one number (merit function) to measure the state of correction of an optical system. This number, which is...
dark current
The current that flows in a photodetector when there is no optical radiation incident on the detector and operating voltages are applied.
dark noise
The noise produced in a photodetector when the photocathode is shielded from all external optical radiation and operating voltages are applied.
dark signal
->
dark current
The current that flows in a photodetector when there is no optical radiation incident on the detector and operating voltages are applied.
data bus
A system incorporated into fiber optic data communications characterized by several spatially distributed terminals that are served with the same multiplexed signal.
deblocking
The removal of optical elements from a block.
decentering
1. The grinding or edging of a lens so that the geometrical center and optical center do not coincide. 2. The shifting of an optical element from the system's optical axis, sometimes done on purpose...
decentration
In a single element, any lack of coincidence between the optical and the mechanical axes. In a lens system, any lack of coincidence of optical axes of the lens elements that make up that system.
decentration aberration
An aberration occurring in a lens system when one or more of the centers of curvature of the optical surfaces do not coincide with the system's axis.
decision-theoretic character recognition
An approach to optical character recognition based on matching the input character against a set of stored prototypes.
decision-tree classification
A structural method of optical character recognition, used where the input media are variable, as in hand-written or multifont documents. A series of questions (such as "Does the character contain a...
deep multiphoton microscopy
Deep multiphoton microscopy is an advanced imaging technique used in biological and biomedical research to visualize structures and processes deep within tissues with high resolution. It combines the...
deep-ultraviolet laser
A deep-ultraviolet (DUV) laser is a type of laser that emits light in the deep ultraviolet region of the electromagnetic spectrum, typically with wavelengths ranging from about 200 nm down to 10 nm....
deeply depressed cladding fiber
An optical fiber, usually a single-mode fiber, that has an outer cladding with nearly the same index of refraction as the core and an inner cladding with a very low index of refraction.
defect function
->
error function
A single number, defined by the computer program or the user that expresses the performance of an optical system. Also known as merit function and defect function, the error function comprises...
definition
The clarity of an optically reproduced image. Definition is produced by the combination of resolution and acutance.
deflection under static load
For an optical table, the amount of displacement that occurs when a heavy load is placed or moved on the surface. To measure deflection under static load, a 113-kg (250 lb) weight is placed in the...
delay line
A device used to delay transmission of a signal for functions such as memory loops, sequential processing or built-in testing. The delay can be achieved by coiling long lengths of coaxial cable or...
delta error
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...
dense wavelength division multiplexing
Dense wavelength division multiplexing (DWDM) is an optical communication technique used to increase the data-carrying capacity of optical fiber networks by simultaneously transmitting multiple...
densitometer
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...
density
->
optical density
A measure of the transmittance through an optical medium. Optical density equals the log to the base 10 of the reciprocal of the transmittance. where τλ is transmittance. In spectroscopy,...
detector noise-limited operation
In optical communication systems, operations in which the amplitude of the pulses, as opposed to their width, determines the distance between repeaters.
detem
A device in which the functions of optical detector and emitter are combined.
DGaO
Deutsche Gesellschaft für angewandte Optik (German Society for Applied Optics)
diamond cutting tool
A tool made by imbedding small particles of diamond in the working edge. In the optical field, the most commonly used diamond tools are glass saws, cup-shaped tools for curve generators, and diamond...
diamond turning
Diamond turning, also known as diamond machining or diamond cutting, is a precision machining process used to produce high-quality optical surfaces and components with extremely tight tolerances. It...
diamondlike carbon film
A very hard, highly transparent coating based on forms of carbon, used to protect optical components from abrasion and chemical damage.
diaphragm
A flanged or plain ring with a restricted aperture, located in an optical system at any of several points, that cuts off marginal light rays not essential to image formation. Diaphragms are used as...
diascope
1. An optical device used for projection of enlarged images of transparencies or lantern slides on a screen. 2. A device designed to hold and backlight transparencies so that their images can be...
diasporometer
In an optical rangefinder, the system of wedges that rotate in opposite directions to aid in the detection of deviation in the image axis.
dichalcogenide
Dichalcogenides are a class of compounds composed of two atoms of a chalcogen element bonded to a single atom of a metal or metalloid element. Chalcogens are the elements in group 16 of the periodic...
dichroic coating
A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively transmit or reflect certain wavelengths of light while simultaneously absorbing...
dichroic mirror
A dichroic mirror, also known as a dichroic beamsplitter or interference filter beamsplitter, is an optical device that selectively reflects or transmits light based on its wavelength. Dichroic...
dichroism
Dichroism refers to the property of certain materials to exhibit different colors or absorbance of light depending on the direction of light propagation or polarization. The term is commonly used in...
dielectric lens
A lens made up of a dielectric material that is capable of influencing radio waves much in the same way an optical lens influences light.
differential interference contrast microscopy
Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast microscopy, is an optical imaging technique used in microscopy to enhance the contrast of transparent...
differential mode attenuation
The variation in attenuation among the propagating modes of an optical fiber.
differential mode delay
Differential mode delay (DMD) is a parameter used to characterize the propagation characteristics of optical fibers, particularly in multimode fiber optic systems. It refers to the difference in...
diffraction
Diffraction is a fundamental wave phenomenon that occurs when a wave encounters an obstacle or aperture, causing the wave to bend around the edges and spread out. This effect is most commonly...
diffraction efficiency
Diffraction efficiency is a measure of how effectively a diffractive optical element (DOE) or diffraction grating directs light into specific diffraction orders or achieves a desired optical effect....
diffraction grating
A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...
diffraction image
->
geometric image
The position and shape of the image of a point source, as predicted by geometric optics alone. The geometric image is to be differentiated from the diffraction image, which is determined from...
diffraction limited
The property of an optical system whereby only the effects of diffraction determine the quality of the image it produces.
diffraction velocimeter
->
laser velocimeter
A system that uses a continuous-wave laser to measure the velocity of an object by focusing the laser beam on the object, perpendicular to its direction of motion. An optical grating receives...
diffractive lens
Any optical device that utilizes diffraction in an image-forming capability. Familiar diffractive lenses are zone plates, holographic lenses, kinoform lenses and binary optics.
diffractive optical processors
Diffractive optical processors are optical devices that utilize diffractive optics principles to perform various computational tasks, such as image processing, pattern recognition, and optical...
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Photonics Dictionary
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