I was just looking through Feynman's QED book (i'm surprised I'd never read it before) and I was wondering if anyone knew of any videos out there that actually experimentally demonstrate how light can be reflected by a diffraction grating even when the incident laser isn't actually POINTING at the grating. Or perhaps something similar where a small mirror is placed on top of a diffraction grating and a laser pointed at the mirror only and yet diffraction effects can be seen. Any links would be greatly appreciated. P.S. I'm looking for a real video, not CGI animations.