I found this press release just yesterday and I'm curious to know how it works: http://www.optware.co.jp/english/what_040823.htm In Figure 1: -Substrate 2 is just a protective cover for the cd. -The photo polymer is the recording layer, but which wavelength(color) is actually causing the polymerization for writing? And which one is reading the hologram? -The gap layers are just there to seperate the dichroic mirror. -The dichoric mirror is basically a wavelength filter that either reflects light or allows light to pass through. -Substrate 1 is just the shiny part of the cd that prevents the light from escaping. Why does the aluminum reflection layer have pits?