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Definitions: K

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A device designed to measure radiant energy, particularly in the thermal region.
Kapitza-Dirac diffraction
The diffraction of a particle by a standing lightwave.
Kell factor
In an interlaced scanning electro-optical system such as television, the system resolution will be less than the number of active scan lines because of the random phase nature of the object being...
Kellner eyepiece
An eyepiece consisting of a planoconvex field lens and a cemented doublet as the eye lens.
The SI unit of temperature equal to 1°C. See absolute temperature scale.
Keplerian astronomical telescope
A simple form of astronomical telescope that uses a fixed objective and a focusable eyepiece. The objective forms an intermediate image in the instrument, resulting in an image that appears upside...
See color perception test equipment; eye test apparatus.
The material lost during a laser cutting or machining operation.
kernel -> convolution kernel
The group of adjacent pixels on which the convolution process is carried out.
Kerr cell
A cell filled with a transparent material that, when placed in a strong electrical field, exhibits double refraction. Since the two polarized elements of an incident light beam travel at different...
Kerr effect
The Kerr effect, named after the physicist John Kerr who first observed it in 1875, is a nonlinear optical phenomenon where the refractive index of a material changes in response to an applied...
Kerr soliton
A Kerr soliton refers to a specific type of soliton, a self-reinforcing wave packet, that arises in nonlinear optical systems due to the Kerr effect. The Kerr effect is the phenomenon where the...
E.I. duPont's trade name for an aramid yarn used as a strength member in the jacket of fiber optic cable.
keyhole welding
The process of binding or attaching larger metal sheets by laser welding. The effect is generated by higher power densities which, while creating a larger weld, produce a vapor that is penetrated by...
keystone distortion
A type of geometrical distortion that brings about a trapezoidal display of a nominally rectangular picture. Usually produced when a picture is projected abnormally to the screen.
kidney-bean effect
A dark region created by spherical aberration of an eyepiece's exit pupil. Because of the aberration, an observer's eye must be at different distances from the eyepiece to view different regions of...
Kikuchi lines
An array of spectral lines formed when a beam of electrons, striking a crystalline solid, is scattered. It is used in the analysis of the crystal structure.
In the SI system, prefix meaning one thousand, 103.
A unit of frequency that equals 1000 cps. Abbreviated kHz.
A unit of energy or work that is equal to 1000 (103) joules. Abbreviated kJ.
kinematic mount
A mount for an optic element or optics assembly, designed so that all six degrees of freedom are singly constrained. This assures that movement will be prevented, while stress will not be introduced...
That portion of physics concerned with motion in the abstract, such as of points or space figures, and separated from its dynamic properties.
A cathode-ray tube that serves as a picture tube in a television receiver. The signal representing the picture intensity is transmitted to the electron gun grid so that the beam intensity varies with...
kinetic cooling
An atmospheric nonlinear process unique to CO2 laser wavelengths, whereby CO2 absorbs 10.6-µm radiation and the CO2 molecules in the (100) vibrational state are excited to the (001) level, and...
Lens which, by altering the phase, efficiently images through a holographic process.
kinoform filter
A computer-generated kinoform used for data processing because of its use of incoherent light and its wide field of view, which facilitates parallel processing of two-dimensional data.
Kirchhoff's law
For any point on a thermal radiator, at thermal equilibrium and for each wavelength, the emissivity in any direction is equal to the absorptance for radiation from the same direction.
A thermionic tube that has a velocity-modulated electron stream and that may be used as a microwave amplifier or oscillator.
knife-edge scanning microscope
An imaging device originally created to image whole mouse brain volumes at microscopic resolution. The main component of the instrument is an automated microtome and microscope capable of producing...
knife-edge test -> Foucault knife-edge test
The Foucault test is performed by moving a knife edge laterally into the image of a small point source. The eye, or a camera, is placed immediately behind the knife edge, and the exit pupil of the...
Knoop hardness
A measurement of the hardness of a material as determined by the penetration depth of a diamond stylus under a specified amount of pressure.
Koehler illumination
A two-stage illuminating system for a microscope in which the source is imaged in the aperture of the substage condenser by an auxiliary condenser, and the substage condenser in turn forms an image...
Koenig-Martens spectrophotometer
A visual, single-unit spectrophotometer with a biprism and a Wollaston prism. The Wollaston prism polarizes coincident images of the two halves of the entrance aperture.
Westinghouse trade name for an alloy of iron, nickel and cobalt, which has the same thermal expansion as glass and therefore is often used for glass-to-metal or ceramic-to-metal seals.
Kramers-Kronig relation
Analysis of the reflection spectrum that allows the determination of the experimental dielectric function.
kron camera
Astronomical detector consisting of a photocathode isolated from the target by a coin value from which electrons are focused on a nuclear emission, producing tracks on the emission. Track density can...
krypton lamp
An arc lamp that has its cavity filled with krypton to produce a light source with unique characteristics.
Kubelka-Munk theory
A two-flux theory in which the radiation is assumed to be composed of two oppositely directed radiation fluxes through a continuous medium. The theory has been widely used to relate the total diffuse...
Kundt effect -> Faraday effect
The Faraday effect, named after the English scientist Michael Faraday, is a phenomenon in physics where the polarization plane of light is rotated when the light passes through a transparent medium...
Pennwalt's trade name for polyvinylidene fluoride, a material used in the jacket of fiber optic cables where low smoke emission is deemed more important than flexibility.
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