Photonics Dictionary: H

A halogen lamp, also known as a tungsten halogen, quartz-halogen, or quartz iodine lamp, is an incandescent lamp that uses a tungsten filament surrounded by a small amount of halogen gas, such as...

Usually a dielectric coating on glass or plastic optics; a coating that is comparable in hardness to glass itself.

The process of subjecting glass to temperature cycling to produce physico-chemical reactions that alter its properties. Similar processes can be accomplished with a laser -- most commonly a CO2,...

A glass filter that transmits visible light while absorbing infrared energy (heat).

Glass that has been specially treated so that it will not shatter when exposed to high temperatures followed by immediate and rapid cooling.

A condition in which the solid inclusions within a glass blank are very numerous, such as 25 or more to the square inch.

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

In plano work, that property of a surface determining that it is convex and contacts a flat test glass at its center.

A camera designed to record at rates exceeding 50 fps. For frame rates up to about 500 fps, an ordinary pull-down mechanism can be used. From 500 to 1000 fps, the film must be moved continuously, the...

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

A glass rhomb that is used in photometry to compare two illuminated surfaces. This is accomplished by the rhomb's angles, which transmit two light beams, one from each of the two surfaces, so that...

An ocular having two planoconvex lenses that are formed from similar glass and that are separated by a space equal to half the sum of their focal lengths. This eyepiece is free of lateral chromatic...