Photonics Dictionary

A lens with aberrations corrected to the point that residual wavefront errors are substantially less than one-quarter the wavelength of the energy being acted upon.

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 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.

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.

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...

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;...

A digital camera is a device that captures and records still images or video in digital format. Unlike traditional film cameras, which use photographic film to capture and store images, digital...

Pictorial information processing in which the processed picture shows a family of equidensity lines or bands coded with different printed patterns or colors.

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...

Digital Imaging and Communications in Medicine (DICOM) is an international standard for medical imaging created by both the National Electrical Manufacturers Association (NEMA) and the American...

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 step-by-step method of reducing the amount of data in a digital video signal to transmit or store a high-quality image. The digitized picture is analyzed, and fine detail and redundant pixels,...

A photosensitizing drug used in conjunction with photodynamic therapy.

In chemistry, the addition of an inert substance to reduce the concentration of a species. In colorimetry, addition of white to a stimulus to reduce its saturation.

An electric or electronic device that regulates the voltage going to a light source as a means of varying the intensity of the light emitted by the source.

The logarithmic method of determining emulsion speeds developed by the German standards organization, Deutscher Normenausschuss, in which the speed of the emulsion is doubled for each increase of...

A two-electrode device with an anode and a cathode that passes current in only one direction. It may be designed as an electron tube or as a semiconductor device.

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...

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...

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.

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

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

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...

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...

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.

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.

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

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...

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

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...

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

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

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

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...

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

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.

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...