optically

As regards sight or the laws of sight; in accordance with or with reference to the science of optics or the use of optical instruments; by optical means.

By optics or sight.

With reference to optics.

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 activity.

See under Refraction.