Photonics Dictionary: H

A defect in the cleaved end face of an optical fiber, defined as multiple surface irregularities across the fiber surface. A less serious imperfection of the same nature is known as mist.

1. In a cathode-ray tube, the glow surrounding a bright spot that appears on the fluorescent screen as the result of the screen's light being reflected by the front and rear surfaces of the tube's...

Describing a surface that is coated with a film of metal of such thickness that it transmits about one-half of the incident light and reflects about one-half.

In the most general sense, the resistance of a solid surface to damage.

An aggravated form of fog in a polished surface caused by the scattering of light. The defects causing haze are larger than those causing fog, but singly are not large enough to be seen by the...

A calorimetric calculation from which the temperature vs. time dependence of any point on a sample can be determined, provided surface and bulk absorption, thermal conductivity and heat transfer...

A series of flanges or other conducting surfaces, usually metal, attached to an electronic device to transmit and dissipate heat that might damage internal circuitry.

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,...

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

A null optic in the form of a concave spherical mirror; used for the test and evaluation of a hyperboloidal aspheric surface.

An optical test table made up of two outer layers or "skins'' bonded to either side of a honeycomblike core, usually of aluminum or steel. It results in equal quality with greatly reduced weight...

Horizontal concentrations that comprise the dominant factor in atmospheric gradient correction. The range bias near due north and due south azimuths coincides with the systematic decrease in surface...

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...

Designed to observe objects below the surface of water. Not to be confused with hygroscopic.

Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a hyperspectral imaging system. In hyperspectral imaging, the electromagnetic spectrum is...