physical optics, on the other hand, has for its ultimate object the elucidation of the question: what is light?
I have not yet seen the respectable relative with my physical optics.
In connection with this matter, the history of physical optics contains an interesting little episode.
But his researches in physical optics constitute his chief title-deed to immortality.
As to the mechanics of the thing, it could only be explained to you by a course of lectures on physical optics.
Indeed, mathematical and physical optics may justly be dated from this time.
There is a phenomenon well known in physical optics as "Haidinger's brushes."