Photonics Dictionary: G

The masking of all openings of an optical transform -- except the hole at the symmetrical center -- with a thin wire gauze to attain a more precise image.

A type of photoconductive detector in which germanium, usually doped with boron, gallium and indium, serves as a semiconductor and can detect up to and beyond 100 µm.

The Golgi staining technique (also called the black reaction) makes it possible to look at the nervous system by rendering neurons visible under light microscopy. After a long process involving...

Also known as amplification. 1. The increase in a signal that is transmitted from one point to another through an amplifier. A material that exhibits gain rather than absorption, at certain...

Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium. This method is distinct from Q-switching and mode-locking, two other common...

Gallium arsenide phosphide (GaAsP) is a semiconductor alloy composed of gallium (Ga), arsenic (As), and phosphorus (P). It is commonly used in the fabrication of optoelectronic devices, particularly...

Gallium nitride (GaN) is a compound made up of gallium (Ga) and nitrogen (N). It is a wide-bandgap semiconductor material that exhibits unique electrical and optical properties. Gallium nitride is...

An instrument for detecting or measuring small electric currents.

An instrument used to detect and measure the energy distribution of gamma rays. It has been used to chart the radioactivity at the lunar surface.

GaN (gallium nitride) distributed feedback (DFB) lasers refer to a specific type of semiconductor laser based on Gallium Nitride materials and designed with a distributed feedback structure. These...

Gallium nitride-based light-emitting diodes (GaN-based LEDs) are semiconductor devices that emit light when an electric current passes through them. These LEDs are constructed using gallium nitride...

A technique for measuring the concentration of any gases. Identical infrared beams are alternately chopped, one passing through a reference cell and the other passing through a cell with the gas...

In detectors, the ability to switch on and off electronically, thus producing the effect of a mechanical shutter.

Also called Geiger-Müller counter. An instrument designed to detect and measure radioactivity through the use of a gas-filled metallic tube containing a needle electrode. Radiation traveling...

A technique used to create an achromatic phase shift based on the principle of geometric phase. The phase shift is experienced by a light beam as a result of a cyclic change in its state of...

Germanium crystal refers to a crystalline form of the element germanium (Ge), which is a metalloid and semiconductor commonly used in various electronic and optical applications. Germanium crystals...

Germicidal ultraviolet (GUV) refers to a specific range of UV radiation that has disinfectant properties capable of killing or inactivating microorganisms, including bacteria, viruses, and fungi. The...

GigE, short for gigabit Ethernet, refers to a standard for high-speed Ethernet communication, capable of transmitting data at rates of up to 1 gigabit per second (Gbps), or 1000 megabits per second...

A device that detects and measures the quantity of exposure to nuclear radiation. It uses a special glass rod that fluoresces when placed under ultraviolet radiation after its exposure to nuclear...

A thermal radiation detector consisting of a small cell with a blackened plastic front face that bulges slightly when heat is received by it. The bulging tilts a small mirror, which, in turn, varies...

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...

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.

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

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...

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...

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...

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...