noun 1. the branch of observational astronomy using telescopes to observe or photograph celestial objects in visible light.
- Optical binary
optical binary See under binary star.
noun 1. an apparatus, as a special table or rigid beam, for the precise positioning of light sources, screens, and optical instruments used for optical and photometric studies, having a ruled bar to which these devices can be attached and along which they can be readily adjusted. noun 1. an apparatus fitted for experimentation in […]
- Optical brightener
noun a chemical substance added to detergents to produce a whitening or brightening effect in fabric or paper Examples Optical brighteners are dyes that absorb light in the ultraviolet and violet region of the electromagnetic spectrum, and re-emit light in the blue region.