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coumarin 314T
An efficient, readily soluble blue-green laser dye.
countersink
The concave portion of a surface, formed on a blank, on which the disk of higher refractive glass will be fused to form a multifocal spectacle lens.
counting chamber
In microscopy, the chamber that is contained on a microscope slide to hold a certain amount of fluid. It is calibrated accurately to determine the number of cells and other elements while the...
coupled rangefinder
A rangefinder on a camera that is integrated with the focusing mechanism so that when an object's range is determined, the camera is automatically in focus.
coupler
1. In color development, the chemical that combines with certain by-products of the development procedure to form a dye. 2. Device for distributing optical power among two or more ports. 3. Device...
coupling efficiency
The fraction of available output from a radiant source that is coupled and transmitted by an optical fiber.
covalent crystal
A crystal formed by covalent bonds that are generally highly directional by nature. The electric characteristics of these crystals classify them as semiconductors.
covered groove
A technique used in integrated optics where a groove is cut on a substrate surface and covered by a thin film to facilitate the construction of filters, resonators, beamsplitters and grating couplers...
coverslip
A coverslip, also known as a cover glass or cover slip, is a thin and flat piece of transparent material typically made of glass or plastic. It is used in microscopy to cover a specimen mounted on a...
Craik-O'Brien effect
Observed when alterations in the luminous sterance at the contour of an object create the illusion of the outer zones appearing darker than the inner regions, despite the consistent luminance of the...
crater lamp
A glow-discharge tube in which the discharge takes place in the conical or crater-shaped depression at one end of the tube.
Crayford focuser
A high-quality focuser that uses rollers rather than gears and offers smooth, precise motion while reducing or eliminating image shift and backlash.
creep
The deformation of a material at high levels of stress, often associated with elevated temperatures.
cresyl violet
Cresyl violet, also known as cresyl violet acetate or cresyl echt violet, is a synthetic organic compound belonging to the class of triarylmethane dyes. It is commonly used in histology and...
cribbing
The breaking of the excess glass from the specified shape.
crimp sleeve
A crimped metal cylinder that holds the connector to the cable through the cable's strength member.
critical absorption wavelength
That wavelength at which the absorption of a given element or system begins to demonstrate an inconstant value.
critical angle
The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is...
critical aperture
In an optical system, the aperture size at which the lens gives its best overall performance.
critical flicker frequency
Relative to a light source, the frequency at which the source appears to fluctuate in light intensity half the time and remains constant during the other half.
critical fusion frequency
The fusion frequency of flicker that is needed just to produce complete fusion and to assure the visual sensation of continuous illumination measured in cycles per second.
critical illumination
Illumination in which the light source is imaged at the object.
critical scattering
Intense scattering in the region of the liquid-gas critical point. At this point the gas will strongly scatter all light to create a vivid opalescent appearance.
Crookes radiometer -> radiometer
A device used to measure the intensity of radiant energy.
cross dispersion
Recombination of only the light that is correctly dispersed by the first stage of a polychromator through its wide intermediate slit (common during Thomson scattering experimentation), which is...
cross roller slide
A positioning slide mechanism with two rows of alternately crisscrossed cylindrical rollers.
cross section
Calculation of the probability of an interaction between two types of particles, such as light absorption, excitation or energy transfers. The probability that one incident particle will interact as...
cross wire
Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects in the field of view. They were formerly made from a single strand of...
cross-correlation
A signal-averaging technique that improves signal-to-noise ratio by comparing a sampled signal with a reference signal bearing some known relation to the received signal.
cross-coupling
1. A defect inherent in a multiple-axis positioning system whereby an adjustment of one axis causes an undesired change in another; its severity depends upon the degree to which the positioning axes...
cross-linked plastic
Plastic in which the polymer chains become irreversibly joined during molding. The cross-linking can be achieved by heating, chemical agents or irradiation.
crossed prisms
The positioning of two Nicol prisms so that their axes are at right angles to each other. With this arrangement, light transmitted by one prism will not be transmitted by the other.
crosshairs -> cross wire
Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects in the field of view. They were formerly made from a single strand of...
crosstalk
The measurable leakage of optical energy from one optical conductor to another. Also known as optical coupling.
crown glass
One of the two principal types of optical glass, the other being flint glass. Crown glass is harder than flint glass, and has a lower index of refraction and lower dispersion. Both types are used in...
CRT -> cathode-ray tube
A vacuum tube with an electron gun at one end and a fluorescent screen at the other. Electrons emitted from a heated filament are accelerated by a series of annular anodes at progressively higher...
crush
A surface scratch or series of scratches formed by mishandling.
crush strength
The physical limit of an optical fiber or cable to withstand an applied force or weight perpendicular to the axis of the fiber.
crust
A stain in a glass surface.
cryogenically cooled LWIR camera
A cryogenically cooled long-wave infrared (LWIR) camera is a specialized thermal imaging device designed to detect infrared radiation in the long-wave infrared spectrum, typically ranging from 8 to...
cryogenics
The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).
cryopump
A vacuum pump in which pressure is reduced by condensing gases on surfaces cryogenically cooled to about 20 K (liquid hydrogen) or 4 K (liquid helium).
cryospectroscopy
The spectrographic analysis of matter that is in a cooled state. Generally, a mechanical refrigerator is used to lower the temperature of the sample, allowing isolation and study of the sample and...
cryostat
A cryostat is a device used to maintain very low temperatures, typically below the boiling point of liquid nitrogen (77 K or -196°C) or even lower. It provides a controlled environment for...
crystal
A solid with a structure that exhibits a basically symmetrical and geometrical arrangement. A crystal may already possess this structure, or it may acquire it through mechanical means. More than 50...
crystal counter
An instrument that is used to detect high-energy particles by the pulse of the current formed when a particle passes through a normally insulating crystal to which a potential difference is applied.
crystal diamagnetism
The unusual and anisotropic diamagnetic quality observed in particular crystals such as those composed of bismuth.
crystal diode
A diode with a semiconducting material, such as germanium or silicon, for one electrode, and a fine wire "whisker'' which lies on the semiconductor, as the other electrode. The low capacitance...
crystal field
The electrostatic field acting locally within a crystal as a result of the microscopic arrangement of atoms and ions in the lattice.
crystal filter
A bandpass filter with piezoelectric crystal components for the passage or impedance of electrical signals of various frequencies.

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