holographic film - physical structure?

Question

hi, anyone can guide mee to where I can find the answers to the questions below:
1_ what is the physical structure of a holographic film. I know we are talking about cristals, I am more intersted in their structure, their separation from each other - if any
2_ after the light and phase have been recorderd, what is their structure then?
I am guessing each will "diffract" (sorry english is not my main language)) the light in every direction, this donee by each cristal (or group of cristals) how does it work physically with its impact on the optic side (is the beam just bouncing back, how is it de-pahased if it is....
is the change of phase due to the height of the layers (with the diferent speed of light in it, making it slower to travel, therefore) when travelling into more of the layer, it will come out dephased more.

I know the above might sound weird, but that is why I ask.
please provide links in the answers.

Answer 1

1. No we are not talking about crystals. Holograms are captured by ordinary photographic film where molecules of silver are produced in the emulsion, producing dark and light areas. The difference is that in a photograph the dark and light match what we see - shadows and bright spots - while in a hologram they match the actual light waves passing through the emulsion. This is why a laser has to be used: it has coherent light and all the waves are exactly the same length and stay in exactly the same place when the image is made.
See the source site for the difference and methods of transmission and reflection holograms (the latter having two layers of emulsion.