Photonics Dictionary

For each mode in an optical waveguide, the term used to describe the process by which an electromagnetic signal is distorted by virtue of the dependence of the phase and group velocities on...

Scattering (other than material scattering) that is attributable to variations of geometry and index profile of the waveguide.

A waveguide is a physical structure or device that is designed to confine and guide electromagnetic waves, such as radio waves, microwaves, or light waves. It is commonly used in communication...

A system that allows the transmission of more than one signal over a common path, by assigning each signal a different frequency band. Also known as frequency division multiplexing.

A photofluorescent compound that, when used with a scintillating substance, absorbs photons and emits related photons having a greater wavelength. In this way a phototube or photocell may employ the...

A fiber for which the difference between the maximum and the minimum refractive index is small, usually less than 1 percent.

The magnetic flux that, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second.

An optical filter so constructed that the density increases progressively from one end to the other, or angularly around a circular disc.

A diffraction pattern sampling unit composed of a 32-element monolithic silicon photodiode array and a readout unit. The intensity on each detector element can be separately read out by means of a...

An optical element having plane-inclined surfaces. Usually the faces are inclined toward one another at very small angles. Wedges divert light toward their thicker portions, and may be circular,...

The Weissenberg method, named after the German physicist Karl Weissenberg, is a technique used in x-ray crystallography for obtaining high-quality diffraction patterns from single crystals. This...

A well plate, also known as a microplate or microtiter plate, is a flat plate with multiple small wells or depressions arranged in a grid pattern. Each well serves as a separate container for holding...

Whispering gallery mode (WGM) refers to a phenomenon in wave physics, particularly in optics, where waves, such as light or sound waves, are trapped and circulate along the periphery of a curved...

A feature of some imaging devices, such as digital cameras, that allows them to compensate for different lighting conditions by adjusting the color balance based on the difference between a white...

The state of a carrier signal that corresponds to maximum picture brightness in a television system.

The random noise having a spectral density that is substantially independent of the frequency over a specified frequency range. White noise is widely used in the random vibration testing of devices.

Whole slide imaging (WSI), also known as virtual slide microscopy or digital pathology, is a technology that involves the digitalization of entire glass slides containing histological or cytological...

A wide-angle lens is a type of camera lens that has a shorter focal length than a standard or normal lens, allowing it to capture a broader field of view. Wide-angle lenses are characterized by their...

Wide-field fluorescence microscopy uses either naturally occurring structures or staining with fluorescent tags that are activated by specific wavelengths of light and then emits a different...

After putting a thick photographic emulsion on a front-faced mirror, and exposing the emulsion to monochromatic incident light normal to the face, Wiener discovered, upon developing the emulsion,...

A method that embraces the classical approach to image restoration and attempts to minimize the mean square difference between the original ungraded signal and the restoration.

A refractometer that has a greater resolving power than a standard refractometer, and that uses a pentagonal prism to split the light from a single slit into two beams.

Specified curved optic intended for maximum collection of light, including off-axis rays, before leaving the exit aperture.

In micropositioning systems, motion (most frequently undesired) about the Z-axis.

A polarizing prism consisting of two calcite prisms cemented such that they deviate the two emerging beams (which are mutually perpendicularly polarized) by nearly equal amounts in opposite...

In microscopy, the clear distance between the specimen being viewed and the first optical element of the objective lens.

An optical data storage device that permits the user to store data (write) and play it back (read), but not to erase or change the stored material.

A Cassegrain telescope having a parabolic primary mirror, a spherical secondary mirror and a zero-power doublet in the converging bundle for aberration correction.

Two flat parallel electrodes that are vertically mounted alongside each other in a cathode-ray tube and produce horizontal deflection of the beam when a difference of potential is applied between...

A window made of glass containing a high percentage of lead or other dense material known to absorb x-rays readily.

The testing by hypothesizing a likely crystal structure, computing a test x-ray diffraction pattern and comparing this to the observed pattern to evaluate a crystal structure.

The series of processes used to identify and evaluate crystal structure by using crystalline solids to diffract x-rays. In the Laue method, radiation of a wide range of wavelengths is transmitted by...

The study of the celestial bodies, relative to x-ray emission. Satellites launched to study x-ray sources have revealed many new classes of galactic and extragalactic sources, as well as the...

The collection and detection of x-rays by virtue of their ionizing properties. The ionization may be perceived directly by a gas-filled ionization chamber, photographically, or by correlating...

One of various types of fluorescent screens used to detect x-ray radiation. Photographic film is mildly sensitive to x-rays, but much more sensitive to light. Hence, in photographing x-ray...

The bending of x-rays by the regular layers of molecules in a crystal acting like a very small diffraction grating. The diffraction pattern so obtained and recorded on film provides a means for...

A film or plate that is usually coated on both sides with a very fast emulsion that is sensitive to x-rays, and used to record x-ray diffraction patterns photographically.

An image intensifier that consists of an evacuated tube with a large input phosphor screen at one end. The phosphor screen is in contact with a light-sensitive photocathode that emits electrons....

Irradiation of a cylindrical crystal with an x-ray beam resulting in Bragg diffraction that produces a slightly enlarged image.

The method of acquiring characteristic x-ray spectra from microscopic samples by use of the combination of a scanning electron microscope and x-ray spectroscopy.

A diagnostic instrument that uses a photocathode design to see a broad range of x-ray radiation by streaking the photographic image continuously in time. It produces time- and space-resolved...

Also known as an anticathode. An electrode or electrode section that is focused upon by an electron beam and that emits x-rays.

The arc formed when the rare gas xenon is excited electrically and emits a brilliant white light. Xenon is used to fill electronic and stroboscopic flashlamps, and also large discharge tubes for...

An instrument for eye surgery that directs intense xenon arc light through the transparent cornea lens to the retina where absorption by the pigment epithelium and the choroid produces heat and...

A printing process of electrostatic electrophotography that uses a photoconductive insulating medium, in conjunction with infrared, visible or ultraviolet radiation, to produce latent...