An Etymological Dictionary of Astronomy and Astrophysics
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A member of a rare class of pulsars, such as the → Crab pulsar and → Vela pulsar, which can be detected in the visible spectrum.

→ optical; → pulsar.

A process in which light energy is used to raise electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction, to pump the active laser medium so as to achieve population inversion. The technique was developed by 1966 Nobel Prize winner Alfred Kastler in the early 1950's.

→ optical; → pumping.

A collection of lens, prisms, mirrors, and/or other devices, placed in some specified configuration, to act on light (reflect, refract, disperse, polarize, etc.) and perform some definite optical function.

→ optical; → system.

Same as → optical depth.

→ optical; → thickness.

The function that provides a full description of the imaging quality of an optical system. A combination of the → modulation transfer function (MTF) and the → phase transfer function (PTF) , the OTF describes the spatial (angular) variation as a function of spatial (angular) frequency.

→ optical; → transfer; → function.

The optical portion of the electromagnetic spectrum that passes through the atmosphere all the way to the ground.

→ optical; → window.

Adverb of → optical.

→ optical + -ly.

Nurâné, from nur, → light, + -âné "-ly;" nurikâné, from nurik, → optical, + -âné "-ly."

Relating to → optical activity.

→ optically; → active.

The qualifier of a medium in which the → optical depth is large, significantly larger than 1.

→ optically; → thick.

A wind with the → sonic point located at large optical depth for continuum. In particular, → Wolf-Rayet star winds are → optically thick. However, the outer parts of W-R winds are → optically thin for continuum, and in those regions the matter flow is driven by the same mechanism as in the winds of OB stars.

→ optically; → thick; → wind.

The qualifier of a medium in which the → optical depth is large, significantly smaller than 1.

→ optically; → thin.

A member of a small subset of quasars consisting of bright radio galaxies whose flux of visible light output can vary by as much as 50% in a single day.

→ optically; → violent; → variable; → quasar.