The short of it is that the holograms you see in gift stores and children's trading cards aren't the same kinds of holograms that are made in laboratories with holographic plates and split laser beams.
The holiday season and especially the Y2K thing has me busy at work during all my waking hours - hopefully when things die down we can pick this topic up again, because it is something that I'm very interested in.
In the meantime, IBM's site has some information about holographic data storage that might be of interest... they've been researching the subject of holographic data storage (and I believe maybe networking) for the longest period of time.
[mailto:firstname.lastname@example.org]On Behalf Of email@example.com Sent: Saturday, December 11, 1999 7:34 PM To: firstname.lastname@example.org
Subject: Re: Holography
cwhipple@VantasInc.com wrote (supposedly):
> "since you split a hologram in two, you get two holograms..."
> When you split a hologram into any number of smaller units, you get a
> degradation of the original hologram. I suppose you could liken it to
I've looked at holograms at the store, and this doesn't seem exactly right. The hologram is like a window, which you look through at a reconstruction of the object. Cutting a hologram in half is like cutting a window pane in half, shrinking the size of the window so you have a smaller hole to look through.
You can still see the object just as clearly as before. The only degradation is that you can't see it from as wide an angle as you could. There is less information present about how the scene looks from other angles that are no longer visible in the hologram (or from the shrunken window).
If you keep shrinking the hologram down, you probably do get degradation eventually, just as you will if you keep shrinking a window. At some point so little light gets through that you can no longer make out what you are seeing. But you have to get it pretty small before this happens.
Prior to that point the degradation is more a matter of a loss of information which was stored only in the other parts of the hologram (like, how the viewed object looks from those angles). It's not like cutting a hologram in half makes the object look any blurrier, at least not the ones I see at the gift store. It doesn't seem at all like line noise.