The Collaborative International Dictionary of English v.0.48:
Optically \Op"tic*al*ly\, adv.
1. By optics or sight.
2. With reference to optics.
Optically active, Optically inactive (Chem. Physics),
terms used of certain isomeric substances which, while
identical with each other in other respects, differ in
this, viz., that they do or do not produce right-handed or
left-handed circular polarization of light. See optical
Optically positive, Optically negative. See under