Photonics Dictionary

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, 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...

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...

A very hard, highly transparent coating based on forms of carbon, used to protect optical components from abrasion and chemical damage.

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...

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...

A mirror coated to reflect cold (white) light while transmitting hot (infrared) energy.

A type of photographic film, often used in microfilming, that is processed by heat treatment, needing no liquid application.

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...

A polarizer that consists of dichroic polarizing material embedded in a plastic sheet, and that transmits light that is almost completely plane polarized with an intensity that is half that of the...

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...

A device used to investigate the dichroism of crystals.

Glass tinted with mixed oxides of neodymium and praseodymium that, unlike most solid materials, have absorption bands that are very narrow and that have very sharp areas.

Die bonding is a critical process in semiconductor manufacturing and microelectronics assembly, where a semiconductor die or chip is attached and electrically connected to a substrate or a package....

Exhibiting the characteristic of materials that are electrical insulators or in which an electric field can be sustained with a minimum dispersion of power. They exhibit nonlinear properties, such as...

A high-reflectance coating consisting of alternating layers of quarter-wave film of a higher refractive index and lower refractive index than the substrate. Such coatings can be made very specific to...

A number that indicates the magnitude of the shift in a solid of positive and negative charges in opposite directions when a voltage is applied across the solid.

A crystal that is characterized by its relatively poor electrical conductance.

A waveguide made up of a dielectric material, such as plastic or mica, in a cylindrical form, through which the waves travel.

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.

The minimum of change in stimulation needed to effect an awareness of change in sensation that is statistically determined.

A lidar (light detection and ranging) technique used in pollution monitoring. Two light beams are emitted simultaneously, one at a wavelength that will be absorbed by the target particles, and the...

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...

A method of coding image data by storing in memory only differences in brightness of each pixel from that of its nearest horizontal neighbors: that is, it is the change in brightness rather than the...

The slope of the curve when output is plotted against input for quantum efficiency in a device.

As a wavefront of light passes by an opaque edge or through an opening, secondary weaker wavefronts are generated, apparently originating at that edge. These secondary wavefronts will interfere with...

The angle that lies between the direction of an incident light beam and any resulting diffracted beam.

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....

A spectrograph that uses a diffraction grating as its dispersive element in place of a prism, and yields greater resolving power, more dispersion and a linear spectrum.

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...

1. The ring patterns of light that seem to encircle particles in the field of a microscope. 2. See Newton's rings.

In spectroscopy, the parallel bands that vary in lightness and darkness or color, and that are formed when light is diffracted by a sample.

Any optical device that utilizes diffraction in an image-forming capability. Familiar diffractive lenses are zone plates, holographic lenses, kinoform lenses and binary optics.

Optical elements that use diffraction to control wavefronts. Diffractive optical elements include diffraction gratings, surface-relief diffractive lenses, holographic optical elements and...

The study of the diffraction of beams of a wave by matter to ascertain the structure of the matter.

The logarithm of the reciprocal of diffuse transmittance. Diffuse density results when a sample is diffusely illuminated.

Light emitted by one or more sources and characterized by a high degree of scatter.

Ratio of diffusely reflected flux to incident flux.

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties of materials, particularly in the field of spectroscopy. Unlike traditional...

A reflecting surface that scatters radiation that is incident on it, thus producing diffuse reflection.

Use of a photoelectric receiver to sense an object's presence by detecting a small amount of the emitter's light that is diffusely reflected by the object.

Transmission accompanied by diffusion or scatter to the extent that there is no regular or direct transmission.

The ratio of diffusely transmitted flux to incident flux.

An optical diffuser is an optical component or material designed to scatter or diffuse light that passes through it. It is used to create a more even or uniform illumination, reduce glare, or soften...

An embossed or marked disk, constructed out of a transparent material and used with a camera system to soften an image.

A vacuum pump in which heated oil or another substance is forced through jets as a vapor that collides with gas molecules and carries them away from the chamber being evacuated.

A cosmetic defect on the surface of an optical element. A dig is nearly equal in terms of its length and width. The size is specified numerically by its average diameter in 1/100 of a millimeter;...