Photonics Dictionary: G

The graphed curve illustrating the directional reflectance of a sample for different angles of collection.

In image processing and machine vision, the rate of change of pixel intensity.

The term gradient-index profile refers to a specific type of refractive index distribution within an optical material. In optics, the refractive index of a material describes how much the speed of...

In a multicrystalline material, the meeting point between crystallites.

Gram-positive bacteria are a group of bacteria that have a thick cell wall composed primarily of a substance called peptidoglycan. This thick peptidoglycan layer retains a stain called crystal violet...

Graphene is a two-dimensional allotrope of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice pattern. It is the basic building block of other carbon-based materials...

Postulated by Einstein in his theory of relativity. They are waves traveling at the speed of light and exerting force on matter in their path. They are produced by changes in the distribution of...

An image consisting of an array of pixels that can have more than two values (black and white). Typically, up to 16 levels are possible per pixel.

Image enhancement operations that involve altering gray-scale values. For instance, brightness sliding involves adding or subtracting an identical brightness value to or from each pixel in an image;...

A porous ceramic substance that is ground to a given optical form and on which a polished plate of glass is sagged by heat application. It is capable of transmitting in a partial vacuum. The glass...

A GRIN (gradient index) lens is a type of optical lens that utilizes a gradient in refractive index across its volume rather than having a uniform refractive index like conventional lenses. This...

Also known as ground level. The lowest energy level of an atom or atomic system. A material in the ground state is not capable of emitting optical radiation. All other states are called excited...

For a given mode propagating in a medium of refractive index n, the velocity of light in vacuum c, divided by the group velocity of the mode. For a plane wave of wavelength l, it is related to the...

A factor derived by equating the incident light on the subject to the required incident light for suitable photography. The lamp-subject-distance then is multiplied by the aperture and solved in...

A wave in which energy is focused near a boundary separating materials having different properties. Propagation of the wave is in a direction parallel to the boundary.

A gyroscope is a mechanical device consisting of a spinning disk or wheel mounted on a spinning axis in such a way that its orientation remains fixed regardless of any movement of its mounting...

A mount that uses a floating suspension and a motor-driven gyroscope to keep a motion picture or still camera at a set angle even though the camera is mounted in a place that subjects it to heavy...