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233 terms

Photonics Dictionary: G

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graded index; gradient index
GRIN lens
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...
The process in the manufacture of an optical system that gives it the required geometric shape.
grinding and polishing machinery
Machinery used to grind and finish a component, such as a lens or prism, to a desired precision. Usually such machines carry a cup-shaped or flat tool (lap) into close contact with the part. An...
grinding tool
A tool of cast iron or another suitable medium used with a slurry of silicon carbide, aluminum oxide or emery for grinding optical surfaces.
graded-index separate confinement heterostructure
Grittington test
A method of determining the abrasion resistance of very hard materials by passing a weighted wiper blade across them in a sand-water slurry for a specified number of times.
ground glass
A plate of glass in which a face has been frosted by grinding or etching. It diffuses light by scattering in directions close to the incoming beam, but the light falls off rapidly at larger angles...
ground state
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...
ground truth
A term variously applied to remote sensing techniques that essentially refers to all parametric conditions that influence the sensor system; includes the quantitative reality that the sensor sees and...
group index
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...
group velocity
For a particular mode, the reciprocal of the rate of change of the phase constant with respect to angular frequency.
grown-junction photocell
A photodiode that has been designed so that the bar of semiconductor material has a PN junction perpendicular to its length and an ohmic contact at each of its ends.
gas-solid chromatography
grating surface emitting
gadolinium scandium gallium garnet
graphics system processors
gain time constant; gain time control
Gires-Tournois interferometer
gas transport laser
Gudden-Pohl effect
The light flash that occurs when an electrical field is applied to a phosphor already excited by ultraviolet radiation.
graphical user interface
guide factor
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...
guided mode
In an optical waveguide, a mode whose field decays monotonically in the transverse direction everywhere external to the core and which does not lose power to radiation. Also called bound mode.
guided ray
In an optical waveguide, a ray that is completely confined to the core.
guided wave
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.
gun camera
A camera accurately aligned to a weapons system to provide a photographic record of system performance.
An optical device that permits the alignment of a gun, cannon or rocket launcher system with its target.
group velocity dispersion
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...
gyroscopic camera mount
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...

Photonics DictionaryG

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