Photonics Dictionary: I

An electroradiographic process that uses ionization of air by x-rays as a basis for forming electrostatic images.

The gas of charged particles that begins approximately 50 km above the surface of the Earth and contains a sufficient quantity of electrons and ions to affect the propagation of radio waves.

The rainbow exhibition of colors, usually caused by interference of light of different wavelengths reflected from superficial layers in the surface of a material.

A mechanical device designed to smoothly vary the effective diameter of a lens, thereby controlling the amount of light allowed through.

The adjustable membrane located just in front of the crystalline lens within the eye. The iris gives the eye its color. See also iris diaphragm.

Radiant flux incident per unit area of a surface. Also called radiant flux density.

A thermosetting material used in the jacket of fiber optic cables.

Application of radiation to an object.

One of a number of nuclides characterized by an identity between their mass numbers, but each having a different atomic number.

Indication of emission brightness with degree of emission from an optical source.

Having the same chromaticity or color.

1. Lines of the same color. 2. A term used in photoelastic stress analysis to refer to the interference fringes produced in birefringent materials.

The points on a photographic negative that are of equal density.

A graphic depiction of the loci of all points in space relative to a laser transmitter at a specific altitude.

With respect to the effect of crystals on lightwaves, the family of curves having constant direction of polarization.

In the context of electronics and optics, an isolator refers to a device that allows the transmission of signals in one direction while attenuating or blocking signals in the opposite direction. The...

An enclosure for a calorimeter that allows measurement of unusually low quantities of power and energy.

A curve or surface having equivalent light intensity.

A direct recording photometer that is designed to scan a photographic negative to determine its points of isodensity.

Free of coma.

Graphic representation of quantified values of image quality whose points all refer to images that are of a constant subjective quality.

Lines of equal atmospheric attenuation in a laser beam.

The slight difference in wavelength of an element's given spectral line observed in comparing different isotopes of that element.

A spectroscopic technique in which an excitation band absorbs laser energy resulting in an electronic transition. The isotopic species may then be measured using a time of flight mass spectrometer....

That property of a material that determines that velocity of propagation within the material is the same for all directions.