Photonics Dictionary

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

Volumetric imaging refers to the capture, visualization, and analysis of three-dimensional (3D) information from a volume of space. Unlike traditional two-dimensional (2D) imaging, which provides...

A vortex phase plate is an optical device designed to impart a phase singularity, commonly referred to as a vortex or phase vortex, onto a light beam. This singularity results in a phase profile...

In the context of electronics and semiconductor manufacturing, a wafer refers to a thin, flat disk or substrate made of a semiconducting material, usually crystalline silicon. Wafers serve as the...

An image intensifier tube in which the photocathode and the output of the microchannel plate are proximity-focused on the microchannel plate input and output phosphor screen, respectively.

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...

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...

The law stating that the just-perceptible increment of stimulus is a constant fraction of the stimulus.

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

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...

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...

An extremely wide emission spectrum generated by the nonlinear effects created when a high peak power from a short-pulse laser is focused into a water or carbon tetrachloride cell. The resulting...

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...

The formula that gives the wavelength of maximum spectral radiant emittance of a perfect blackbody: λmax = 2898/T(µm) The radiation at this λmax can be calculated as follows:...

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

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

1. In a plane Cartesian coordinate system, the horizontal axis, or axis in the left to right direction. 2. In a quartz crystal structure, the refrence axis.

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 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...

An instrument that uses a crystal to diffract x-rays for the measurement of the intensities of the diffracted rays.

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.

1. In a plane Cartesian coordinate system, the vertical axis orthogonal to the X-axis. 2. In a quartz crystal structure, the line perpendicular to two opposite parallel faces of the crystal.

The vertical deflection of an image on a cathode-ray tube screen.

The method by which Thomas Young in 1802 disproved Newton's corpuscular theory of light by the formation of interference patterns between two beams of light from the same source. This was produced by...

The removal of the zero-order component of the Fourier spectrum distribution of an object with a small, opaque absorber or reflector in the Fourier plane, to produce images that appear bright on a...

A quarter- or half-wave retarder made from two plates of quartz, mica or polymer with their fast axes crossed; the difference in thickness between the two plates determines the retardance. Zero-order...

A polycrystalline material that transmits in the infrared; it is used as a phosphor in x-ray and television screens.

Also known as zonal axis. The axis positioned through the center of a crystal that is parallel to a zone edge.

1. In a polished surface, concentric waves that appear as zones in Newton's rings when a test glass is applied. 2. An arrangement of crystal faces that come together in a series of edges, all of...