Photonics Dictionary

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...

A glow-discharge tube in which the discharge takes place in the conical or crater-shaped depression at one end of the tube.

A high-quality focuser that uses rollers rather than gears and offers smooth, precise motion while reducing or eliminating image shift and backlash.

The deformation of a material at high levels of stress, often associated with elevated temperatures.

The breaking of the excess glass from the specified shape.

A crimped metal cylinder that holds the connector to the cable through the cable's strength member.

That wavelength at which the absorption of a given element or system begins to demonstrate an inconstant value.

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...

In an optical system, the aperture size at which the lens gives its best overall performance.

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.

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.

Illumination in which the light source is imaged at the object.

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.

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...

A positioning slide mechanism with two rows of alternately crisscrossed cylindrical rollers.

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...

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...

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.

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...

Plastic in which the polymer chains become irreversibly joined during molding. The cross-linking can be achieved by heating, chemical agents or irradiation.

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.

The measurable leakage of optical energy from one optical conductor to another. Also known as optical coupling.

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...

A surface scratch or series of scratches formed by mishandling.

The physical limit of an optical fiber or cable to withstand an applied force or weight perpendicular to the axis of the fiber.

A stain in a glass surface.

The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).

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).

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...

A device used to maintain near-absolute temperatures for experimental procedures.

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...

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.

The unusual and anisotropic diamagnetic quality observed in particular crystals such as those composed of bismuth.

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...

The electrostatic field acting locally within a crystal as a result of the microscopic arrangement of atoms and ions in the lattice.

A bandpass filter with piezoelectric crystal components for the passage or impedance of electrical signals of various frequencies.

A crystal that may serve as a diffraction grating if mounted effectively.