Re: [tech-3d] Holography

[Peter Homer <P.J.Homer@xxxxxxxxxxxxx>]

>>>Furthermore one explanation of how holograms work is that they behave
>as concave mirrors, with a >>bleached white light reflection hologram for
>instance the multiple layers of exposed emulsion would actually >>be
>curved because the wave front from the original object close to the plate
>would be strongly curved. >>Even with transmission holograms the curved
>surfaces are at angle because the reference beam would >>have come in at
>an angle so the light can still be though of as reflected by concave
>mirrors even though it is >>transmitted.
>
>I suggest that you read a good book about holography. The way they work
>is well understood and documented.
>
>Bob

Which one do you recomend, this explanation is not my own it came from a book and before I read it I had already come across explanations based on diffraction and refraction and these do seem to be in a majority. I did say that this was ONE explanation and actualy I had only seen it in one book but when I tried to check it in my local library they no longer had it. They did however have another book "Homemade" Holograms" John Lovine which also gives this explanation which he refers to as the "Geometric Model" devised by Dr. T.H.Jeong. This he regards as a working model easier to understand than the diffraction model because it does not require math to be understood. He does later go into the diffraction model and considers that the true model.Personaly I think all three could play a part but varying according to what type of hologram is involved and whether or not it is bleached. Reflection holograms which are invariably bleached can shurely be thought of as a type of mirror b!
leached transmission must depend
 more on refraction and the classic unbleached transmission hologram on diffraction.  P.J.Homer 




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