Photonics Dictionary: D

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...

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

A value used to designate the relative sensitivity of a detector. The higher the D* value, the better the detector.

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...

The current that flows in a photodetector when there is no optical radiation incident on the detector and operating voltages are applied.

The noise produced in a photodetector when the photocathode is shielded from all external optical radiation and operating voltages are applied.

A technique whereby the sample is illuminated by a hollow cone of light larger than the acceptance angle of the objective, so that only scattered light is seen, revealing any irregularities of the...

A photomicrographic recording technique that utilizes dark-field illumination to render an image of an object having a refractive index much like that of the medium holding it. The object may be...

A method of storing digital data using techniques that consume less memory space than basic methods do. See differential pulse code modulation; run end coding; run length coding.

Deep learning is a subset of machine learning that involves the use of artificial neural networks to model and solve complex problems. The term "deep" in deep learning refers to the use of deep...

Deep ultraviolet (DUV or deep-UV) refers to a specific range of ultraviolet light with shorter wavelengths than those in the UV-A and UV-B regions. The exact wavelength range considered as DUV can...

The interval between direction of signal to a light-emitting diode and attainment of 10 percent output current in the photodetector.

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

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...

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...

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

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.

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...

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...

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

In an optical rangefinder, the system of wedges that rotate in opposite directions to aid in the detection of deviation in the image axis.

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...

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...

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....

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 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...

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...

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

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...

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.

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...

Digital holographic microscopy (DHM) is an advanced imaging technique that combines holography and digital image processing to capture and reconstruct three-dimensional images of objects. This method...

The technique by which an analog image is converted by any of several means into a finite array of points, each represented by some numerical value. Once created, this array can be the basis of a...

Digital signal processing (DSP) refers to the manipulation and analysis of signals, which are representations of physical quantities that vary over time or space. In the context of DSP, these signals...

A digital twin refers to a virtual representation or digital counterpart of a physical object, system, or process. This digital replica is created using real-time data and simulation models, allowing...

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...

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...