An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

An instrument for measuring the amount of light.

→ photo- + → -metry.

An instrument designed to measure the intensity of a particular spectral line or a series of spectral lines.

→ spectro-; → photometer.

A photometer in which an → absorbing wedge is inserted in the brighter of two beams until the flux densities of the two light sources are equal.

→ wedge; → photometer.