Photonics Dictionary: A

The propagation constant evaluated along the axis of a waveguide, that is, in the direction of transmission. Also called axial propagation wave number.

An instrument that uses optical filtration in order to measure the transmittance for a discrete range or specific number of wavelengths.

Any of a series of radioactive elements with atomic numbers ranging from 89 to 103.

1. Synonymous with radioactivity. The intensity of a radioactive source illustrated as the number of atoms disintegrating in unit time, or as the number of scintillations or other effects observed...

In display technology, an expression of resolution given by the number of pixels in both the horizontal and the vertical axes of a cathode-ray tube or similar device.

A support device in which a column or chamber of air permits the free travel of a mobile part. In optical mounting and positioning equipment, air bearings are of two types, linear or rotary,...

An optical tooling instrument consisting of an objective lens, a focusing lens, an optical micrometer, a reticle and an eyepiece. The alignment telescope projects a precise line of sight to which a...

A luminous display of numbers and the letters of the alphabet.

The all-encompassing noise associated with a given environment, usually being a composite of a number of sources, far and near.

The transparent fluid that fills the portion of the eye between the cornea and the eye lens (the anterior chamber).

An aspheric lens is a type of lens whose surface profiles deviate from the traditional spherical shape. Unlike spherical lenses, which have a constant curvature across their surfaces, aspheric lenses...

The analysis of the atomic structure of a sample by means of a source radiation that is absorbed and emitted by the sample with lines corresponding to the number and arrangement of atoms. Generally a...

The number of molecules in one gram mole of a substance, numerically approximated by 6.02 x 1023.