Left to one's choice; not required or mandatory (Dictionary.com).
Any of various instruments for measuring refractive errors of the eye.
From opto- "vision; eye; optis," combining form from Gk. optos "seen, visible," from opsesthai "be going to see," related to ops "eye;" → -meter.
Fr.: optique physique
The branch of optics concerned with the wave properties of light, → diffraction, → polarization, and other phenomena for which the ray approximation of → geometric optics is not valid. Also called → wave optics.
In general, pertaining to or affording an overall view.
M.L. synopticus, from Gk. synoptikos, from synop-, → synopsis, + -tikos.
Fr.: carte synoptique
1) Sun: A map that displays positions of certain events
(e.g., → sunspots, → faculae,
→ filaments, etc.) observed during one solar rotation.
Fr.: optique ondulatoire
The branch of optics that analyzes the electromagnetic radiation in terms of its wave characteristics. Also called → physical optics.