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Photonics Dictionary: H

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Hertzian waves
The radio waves of the electromagnetic spectrum that have frequencies of up to 10,000 megacycles per second.
heterochromatic light
Radiation consisting of more than a single wavelength in the visible region of the spectrum.
heterochromatic photometry
Light measurement by comparison of the luminances of unlike chromaticities.
heterodyne
The interaction between two oscillations of unlike frequencies that forms other oscillations, specifically those with a frequency equal to the frequency difference of the former oscillations.
heterodyne receiver
A type of receiver that uses a local oscillator at a frequency deliberately offset from that of the incoming signal. It is less sensitive than a homodyne receiver, but easier to build because it...
heterodyning
In optical communications, the translation of optical signals into radio signals, lowering their frequency in detection from greater than 1014 Hz to less than 1010 Hz, so that further signal...
heteroexcimer -> exciplex
The term "excimer," strictly used, refers to excited species made by combination of two identical moieties, atoms or molecules. Excited complexes that do not fall into this category are...
heterogeneous
Property of a substance whose volume elements differ in composition and optical properties.
heterojunction
A junction between semiconductors that differ in their doping level conductivities, and also in their atomic or alloy composition.
heteropolymerization
The combination of more than one type of small-molecule monomer into a polymer.
heterostructures
A method used in integrated optics; formed by growing an epitaxial layer of active material, removing it from its base and splicing it onto a passive substrate.
HEX
heat exchanger unit
HF
high frequency
HFS
hyperfine structure
HID
high-intensity discharge
high
In plano work, that property of a surface determining that it is convex and contacts a flat test glass at its center.
high contrast
A term used to describe a photograph, film or television picture where the values for black and white areas are at or near their limits, thereby giving the maximum degree of difference between them.
high dynamic range
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
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...
high-content screening
Also known as HCS, an analytical method designed to collect statistically relevant amounts of quantitative data on many parallel cell populations or processes within cells through the combination of...
high-density storage
Extensive data storage in the form of bits, with the use of high-resolution photographic materials and optics, and generally a laser.
high-excitation potential -> excitation potential
The amount of energy required to raise the energy level of an atom; a necessity if the atom is to radiate energy. High excitation potential is the amount of energy in the upper state of the...
high-frequency distortion
Distortion of the high frequencies of a signal. In television, the term generally applies to frequencies above the 15.7 kHz line frequency.
high-gain screen
A screen with a reflected or transmitted light beam that is confined to a much smaller bundle than was received by the screen, thereby resulting in a higher luminance.
high-index-contrast subwavelength grating
A superthin, highly reflective mirror.
high-loss fiber
Optical fiber in which the attenuation exceeds the normally acceptable level for long-haul or data communications use.
high-pass filter
A filter possessing one transmission band that extends from a cutoff frequency other than zero to frequency at infinity.
high-performance parallel interface
A very high bandwidth communication line often used in fiber optics.
high-pressure cloud chamber
A cloud chamber designed to maintain the gas within it at a high pressure as a means of reducing the range of the high-energy particles and, subsequently, increasing the chances of observing...
high-resolution visible sensor
A satellite-borne remote sensing device capable of transmitting images at 10 and 20 m resolution from an altitude of 830 km, each sensor covering a ground area of 60 km, by means of a folded...
high-speed holography
The holographic recording of sequences of high-speed phenomena. With a multiple beam laser, multiple holograms that depict rapid events can be formed on a single medium.
high-speed motion camera
A high-speed motion camera, also known as a high-speed camera or slow-motion camera, is a specialized imaging device designed to capture fast-moving events or phenomena at extremely high frame rates....
high-speed movie camera
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...
high-speed photography
Photography involving the recording of events that occur too fast to be perceived by the human eye or recorded by conventional photographic techniques. See high-speed movie camera; high-speed...
high-speed radiography
A method of producing x-ray exposures as short as 0.03 µs; the primary application is in ballistic radiography.
high-speed shutter
A shutter actuated by means other than mechanical springs for timings on the order of nanoseconds. The shutter is used in the photography of rapid moving objects or events.
high-speed still camera
A still camera with a shutter capable of opening for a time as short as a fraction of a microsecond. An electronically operated Kerr cell often is employed.
high-vacuum tube
An electron tube whose electrical characteristics will not be affected by gaseous ionization because of its high degree of evacuation. Also known as a hard tube.
high-voltage electron microscope
An imaging device whose technology contributes three specific advantages: ability to study large solid specimens that exhibit behavior in bulk; conduction of in situ studies of radiation damage; and...
highlight
The portion of a reproduced image having the greatest luminance.
hill cloud lens
A fish-eye lens designed to photograph cloud formations over the entire visible sky.
himawari
A system of Japanese origin that utilizes Fresnel lenses and a fiber optic network to transmit sunlight to otherwise inaccessible areas.
Hindle sphere
A null optic in the form of a concave spherical mirror; used for the test and evaluation of a hyperboloidal aspheric surface.
HIP
hot isostatic pressing
HIPPI
high-performance parallel interface
HIRF
high-intensity radio frequency
histochemical staining
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...
histogram
A graphic representation of a distribution function such as frequency by means of rectangles whose widths represent the intervals into which the observed values' range is divided and whose heights...
histology
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...
historadiography
Techniques used in biology to produce microradiographs of cells, tissues or small organisms.

Photonics DictionaryH

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