Optical waveguide lightmode spectroscopy utilizes the change in resonance angle of polarized light diffracted by a grating and incoupled into a thin waveguide layer upon binding.

to bring a weapon to the charge

Consequently many concepts suitable for the camera loose their sharpness when applied to the eye. For example, because of heterocentricity, the eye has no optical axis as traditionally defined; at best one has to be satisfied with an approximate optical axis.

Bears are at their most dangerous when taken by surprise... If you do happen to come across one, you should exit stage left at normal pace (you won't outrun a bear) and without your picnic basket..