I'm an electrical engineer who recently started working with these near eye optics like this one https://www.trulifeoptics.com/ It looks like a microscope slide but it's a waveguide that transports a display from a little LCD screen to a clear section in front of the users eye. I understand that it combined with the pupil of the eye generates the image that I see.
I understand waveguides from an electrical point of view (and somewhat of an optical one). What I'm curious about is how they make these holographic gratings that couple the image in and out of the waveguide. I don't even know what they are. Are they grinding tiny little aberrations into a sheet of glass, or is it an etching process, or laser? I guess if it was plastic it could be molded like a CD is?
I'm also curious about how why it's called holographic. Holographic just conjures up images of credit cards security stickers and Nova programs from the late 80s for me :)