White light reflection holograms

[Tom13147]

Hi everyone,

 

I was looking for some help with understanding how holograms work. In particular, the reflection holograms, artwork or those you find on credit cards that work with white light.

As far as i understood, with holograms in general you only get a reconstruction of the object forming when the hologram is illuminated with the same coherent reference source used to create it.

 

But with refelection holograms this is clearly not the case as you don't need a coherent OR monochromatic source to get an object forming. why is this?

 

any help would be great.

 

Tom

[between3and26characterslon]

This might explain a bit about what is going on

 

http://www.vega.org.uk/video/programme/45

 

skip the first 25 minutes or so because it's all just preamble and isn't necessary, though if you have the time it is good to watch Feynman, he can be quite amusing