GaAs: Gallium Arsenide, a material used in the detectors of some night vision (image intensified, or I2) devices.
Gain: Functionally similar to ‘contrast’ in a visual system, gain sets the span between the minimum and maximum thermal intensities that can be imaged simultaneously.
Germanium: An material commonly used for optical elements such as lenses or windows in LWIR systems. While this material transmits in the LWIR region, it is opaque in the visible region, appearing black. Germanium is extremely expensive to process, and is a driving factor in the cost of many thermal imaging systems.
Gram-calorie: See Calorie.
Graybody: An “idealized” non-blackbody, in which the emissivity is assumed constant with respect to wavelength.
GHz: Acronym for Gigahertz, equal to one billion (109) Hertz.
