PI Physik Instrumente - Microscope Stages LB ROS 11/24

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Opto Diode Corp. - Detector Spotlight 10-24 MR

Meadowlark Optics - Wave Plates 6/24 MR 2024

8,726 terms

Photonics Dictionary

graduated refractive index -> graded index

Descriptive of an optical fiber having a core refractive index that decreases almost parabolically and radially outward toward the cladding. This type of fiber combines high bandwidth with moderately...

grain boundary

In a multicrystalline material, the meeting point between crystallites.

grain isolating diaphragm

In a microscope, the diaphragm located between the Bertrand lens and the eyepiece, which is closed during conoscopic viewing to restrict the interference figures to that of a crystal lying on the...

gram negative

Gram-negative bacteria are a group of bacteria that possess a cell envelope composed of a thin layer of peptidoglycan surrounded by an outer membrane. This outer membrane contains lipopolysaccharides...

gram positive

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...

gram

Unit of mass in the SI system.

graphecon

An electron tube having two electron guns, one on each side of the storage medium, to encode the information onto the medium, and to read and simultaneously erase the electrostatic encoding.

graphene

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...

graser

An acronym of gamma ray amplification by stimulated emission of radiation. It is a gamma ray laser that operates between energy levels established by metastable isomeric transitions in the nucleus.

graser

gamma ray amplification by stimulated emission of radiation

Grashof number

Formula used in convection study to express the ratio of buoyant force to viscous force.

graticule

The British term for reticle.

grating

A framework or latticework having an even arrangement of rods, or any other long narrow objects with interstices between them, used to disperse light or other radiation by interference between wave...

grating beamsplitter

A grating beamsplitter is an optical device that utilizes the principles of diffraction to split a beam of light into multiple beams, often redirecting them at specific angles. It is based on the...

grating monochromator

An optical instrument used to isolate a narrow bandwidth of optical radiation using a diffraction grating as the dispersive element. See also monochromator.

grating prism

A specific, right-angle prism having a transmission grating replicated on its hypotenuse face and used in applications requiring a system that can produce in-line viewing for one wavelength.

grating spectrograph -> spectrograph

An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a prism or a diffraction grating. A concave grating requires no other means...

grating spectrometer

A spectrometer that uses a grating to diffract light into specific wavelengths.

grating spectroscope

A spectroscope having a diffraction grating for the resolution of light of various wavelengths.

grating substrate

The substrate upon which a diffraction grating will be ruled. It must be dimensionally stable, and the surface must be polished to an accurate flat or spherical form as required by the grating. The...

gravimeter

An instrument capable of precise measurements of the Earth's gravity. This permits the detection of small changes in local height that indicate changes in the Earth's crust and subsurface density.

gravitational imaging

A process used to detect minute gravitational fields and to display images from objects by means of radiated gravitational imagery.

gravitational lens

The effect of a powerful gravitational field on light traveling through the field. This effect is detectable in astronomical observations when light from a distant source passes a massive object...

gravitational waves

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...

gray body

A temperature radiator whose spectral emissivity at all wavelengths is in constant ratio (less than unity) to that of a complete radiator at the same temperature.

gray filter -> neutral density filter

A light filter that equally decreases the intensity of all wavelengths of light without altering the relative spectral distribution of the energy.

gray levels

In image processing, machine vision and television, discrete brightness values quantized for a group of pixels. They can range from white, through various shades of gray, to black.

gray scale

In image processing, the range of available gray levels. In an 8-bit system, the gray scale contains values from 0 to 255.

gray scales

Transparencies that represent progressive steps in the amount of transmitted radiation for administering predetermined amounts of radiation to a radiation-sensitive substance. The steps are...

gray

1. A measure of absorbed dose, equal to the energy imparted by ionizing radiation to a mass of matter corresponding to 1 J per kilogram. 2. A term used to denote an incompletely polished surface that...

gray-scale image

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.

gray-scale modification

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;...

grazing emergence

A condition in which an emergent ray is perpendicular to the normal of the emergent surface of a medium.

grazing incidence

Light striking a surface at an angle almost perpendicular to the normal.

green block

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...

green disc

Familiar term for CD/I disc. The CD/I standard also is known as the green standard.

Greenough microscope

A form of a stereoscopic microscope having paired objectives, prisms and eyepieces, and invented by H. Greenough.

Gregorian telescope

A telescope with an ellipsoidal secondary concave mirror that reflects rays from a parabolic primary mirror through an opening in the center of the primary, where the image is viewed with an eyepiece.

grenz rays

The soft x-rays used in the industrial radiography of materials having too small a range of densities to produce an image with normal x-rays.

GRIN

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...

grinding

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.

GRINSCH

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...

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