Glossary
G
- GaAsP photomultiplier tube (GaAsP PMT)
- A photomultiplier tube using a gallium arsenide phosphide (GaAsP) photocathode, which provides high sensitivity in the visible spectrum, especially the red.
- See also: photomultiplier tube, multi-alkali photomultiplier tube
- Gaussian beam
- A beam of light with a wavefront profile that can be modeled by a Gaussian function. TEM00 beams have a Gaussian profile.
- See also: Bessel beam, Airy beam
- Gaussian optics
- A system of optical analysis that utilizes the paraxial approximation to simplify modeling of the behavior of light in geometric optics and ray tracing. This system only uses paraxial rays - those that make a small angle with respect to the optic axis.
- Synonyms: small-angle approximation
- See also: geometric optics, ray tracing
- generalized pupil function
- see pupil function
- geometric optics
- A system of optical analysis wherein light is described as rays, providing the basis for ray tracing. Effects such as reflection and refraction are considered while others, such as diffraction and interference, are ignored.
- Synonyms: geometrical optics, ray optics
- See also: Gaussian optics, ray tracing, wave optics
- geometric phase
- The relative phase difference between two beams due exclusively to having undergone different changes in polarization.
- Synonyms: Pancharatnam-Berry geometric phase
- See also: polarization
- geometrical optics
- see geometric optics
- gliding stage
- A type of stage consisting of two surfaces, where the bottom one is fixed to the microscope and the top one can be freely translated in the lateral directions.
- See also: stage
- glycerin immersion objectives
- Objective lenses that utilize glycerin as an immersion medium (refractive index = 1.473). Typically featuring long working distance and wide-ranging correction collars, they are optimal for imaging deep, cleared tissue samples.
- See also: objective lens, tissue clearing, refractive index
- gout testing
- The use of polarized light microscopy to identify gout crystals based on their birefringence.
- See also: polarized light microscopy, birefringence
- gradient-index lens (GRIN)
- A lens with spatially-varied refractive index, designed to reduce optical aberrations.
- See also: refractive index, spherical aberration, perfect lens
- graphical user interface (GUI)
- A software tool that enables user interaction. In microscopy software, this is usually a window that displays images from the microscope, and allows users to control acquisition functions or analyze images.
- graticule
- A grid like pattern that provides overlaid reference distance over some field of view. For example, this could be a target printed on microscope eyepieces that enable sample centration or micrometry.
- Synonyms: reticle
- See also: micrometry
- Greenough stereomicroscope
- A stereo microscope design featuring twin, inwardly inclined objective-eyepiece lightpaths to produce a stereo effect.
- See also: stereomicroscope
- ground glass
- Ground glass has a roughened surface and is generally used as a light diffuser to obtain homogenous lighting.
- See also: diffuser
- ground truth
- The real distribution of sample features and usually below the resolving capacity of an imaging system.
