Science Forums 2

[johnfp]

All real holograms (not the star wars fake stuff) acts as a lens to take the illuminating light and focus it to the wave front of the original object light. This is done by all those interference fringes being captured in the emlsion.

So to explain simply, think of a fresnel lens. It is thin yet acts as a thicker lense due to the groves. Well it's basically the same principle in manking a Holographic Optical Element (HOE). But instead of etched groves you have either dark and light groves (fringes) in silver halide or two different types of groves (fringes) with relation to their index of refraction as in Dichromated Gelatin (DCG). Most HUDS and HOES are made from DCG as they can approach replay efficiency of 95%.

DCG is what I have been playing with now for years. I make my own emulsion and coat my own plates. My avitar is a hologram I made and you can see how bright it is.