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From: root@cca.ucsf.edu (Systems Staff)
Newsgroups: comp.graphics
Subject: What's a hologram?
Summary: What is the definition of hologram?
Message-ID: <2330@ucsfcca.ucsf.edu>
Date: 25 Aug 89 02:02:03 GMT
References: <4791@portia.Stanford.EDU> <1746@dover.sps.mot.com>
Organization: Computer Center, UCSF
Lines: 37


I see some quite different things being called "holograms" and
would like to know what's what.

There are what I have understood to be holograms which are formed
by beam splitting and interference pattern generation on a
photographic medium. These are viewed with a matching coherent
light source and form an image by diffraction effects.

OK, that's what I've been told.

Now, I've seen some things which are just multiple image prints
with a surface molded to form a lens array to get some of the
variable perspective image effects that a hologram as described
above yields (but greatly inferior).

I hear people calling these things "holograms". Is there really
something holographic about them? Or is it just the usual case
of ripping off terminology to describe an imitation?

Then I hear about "white light holograms" in contexts that suggest
"genuine" holography but obviously involve a difference in process.

Can someone who really knows what's going on shed a litlle light?
I daresay I'm not the only one who finds this less than clear.

 Thos Sumner       Internet: thos@cca.ucsf.edu
 (The I.G.)        UUCP: ...ucbvax!ucsfcgl!cca.ucsf!thos
                   BITNET:  thos@ucsfcca

 U.S. Mail:  Thos Sumner, Computer Center, Rm U-76, UCSF
             San Francisco, CA 94143-0704 USA

I hear nothing in life is certain but death and taxes -- and they're
working on death.

#include <disclaimer.std>