Photonics Dictionary: H

The line that divides the two half-images in a coincidence rangefinder. The two halves of the images formed by the two objectives of the instrument must be brought to a point where they coincide...

Triggering a laser at a predetermined time by pumping it to a level just below its threshold and then using an auxiliary source that quickly pumps it above threshold. Means of achieving it in laser...

The term half bandwidth (HBW) generally refers to the width of a spectral band or frequency range at half of its maximum amplitude. It is commonly used in the context of signal processing, optics,...

1. The value on either the leading or the trailing edge of a laser pulse at which the power is one-half of its maximum value. 2. The wavelength at which a filter is transmitting one-half of its peak...

High-modulus elastic fibers that exhibit the following differences from conventional elastic fibers: Increasing temperature decreases recovery force (the fibers are enthalpic vs. conventionally...

The process of sealing laser components by means of frit seals, welding or bonding rather than using epoxy.

Harmonic generation refers to a nonlinear optical process in which incoming photons interact with a material and produce new photons at integer multiples of the frequency of the incoming photons....

A type of cooling system in which one fluid is used to carry heat off another without direct contact between the two.

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,...

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

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...

The total fusion and sealing of materials, or usually an enclosure, to ensure that they are airtight.

High dynamic range (HDR) refers to a technology that allows for a broader and more dynamic range of luminosity in visual content, such as images or videos. It is particularly associated with displays...

High harmonic generation (HHG) refers to a nonlinear optical process in which intense laser light interacts with a gaseous medium, typically an atom or a molecule, to produce harmonics of the...

Distortion of the high frequencies of a signal. In television, the term generally applies to frequencies above the 15.7 kHz line frequency.

A very high bandwidth communication line often used in fiber optics.

Histochemical staining is a laboratory technique used in biology and medicine to visualize specific chemical components within biological tissues. This technique involves the application of various...

Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs at the cellular and subcellular levels. It is a field that focuses on the...

The dip or gap in the profile of a laser beam's line width when it is both homogeneously and inhomogeneously broadened. When an inhomogeneously broadened spectral line is saturated by incident light,...

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 holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional reconstructions of transparent or weakly scattering objects with high...

The broadening of a laser's line width in a way that affects every atom (or molecule), and thus the whole system, in the same manner. Examples are collision broadening, and natural or intrinsic...

In television, the period during which the electron beam is cut off while the raster returns from the right-hand side of the screen to the left.

In television, the number of individual pixels that can be distinguished in a horizontal scanning line; also called horizontal definition.

The rotation of an instrument (or the line of sight of an optical system) in a horizontal plane; transverse.

A method of manufacturing polycrystalline infrared-transmitting optical fiber by heating a single halide crystal billet and forcing it through a die.

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...

A hydrogel is a three-dimensional network of polymer chains that are hydrophilic, meaning they have a strong affinity for water. This network structure allows hydrogels to absorb and retain large...

A gas laser having a mixture of gases that makes it useful in the lab. The mixture of gases flows through a pressure and gas-flow-rate-regulated, sealed vessel with such a gain that only the...

Hydrophobic is a term used to describe substances or materials that repel or do not readily interact with water. The word hydrophobic comes from the Greek words "hydro," meaning water, and "phobos,"...

The splitting of an element's spectral line as the result of the interactions between the electron spin and the spins of adjacent magnetic nuclei, or the presence of several isotopes in the sample...

A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide range of wavelengths within the electromagnetic spectrum, typically from...