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From: kenb@amc-gw.amc.com (Ken Birdwell)
Newsgroups: comp.graphics
Subject: Wall sized video
Keywords: lasers, video
Message-ID: <2982@amc-gw.amc.com>
Date: 6 Sep 90 01:58:16 GMT
References: <1990Sep3.033831.2543@dhw68k.cts.com> <7192@eos.UUCP> <1149@mti.mti.com>
Reply-To: kenb@belltown.amc.com (Ken Birdwell)
Distribution: na
Organization: Applied Microsystems, Redmond, WA
Lines: 44


With all this talk about video walls (walls of CRT's) got me thinking about 
real wall sized TV.  Around 1980 a friend of mine was working on a project for 
video projection that used a laser as the scanning beam.  The idea was that 
since you can get lasers in the exact frequency you want you can get great 
colors as bright as you want (well, until the reflecting surface melts).   
The goal was to use it as a table sized CAD-layout system (5' by 3' and 16k 
by 16k pixels) but as a first step they built a wall sized (8' by 6' and 512
by 480 pixels) TV projector.  Well, the first time I saw it I was blown away 
by the intensity of the colors (they were showing Barbrella) and the 
brightness (shown in a well lighted room).  Unfortunitly the next thing 
I and everyone else noticed was speckel (sp?).  For those of you who dont know 
what speckel is, If you've ever seen a laser show its the fuzzyness around 
where the beam hits.  Anyway, it totally ruined the picture and they were 
unable to get rid of it.  They had reams and reams of physicists come in and 
try to solve the problem.  Each one knew what is was, (something different 
every time), and each one had a solution that didnt work.  The most popular 
explanation was that it was a second order quantum effect??? but no one knew 
what to do about it.  One of the worst problems was that it seemed to 
get bigger the farther away to where from the reflecting surface. They tried 
it in a vacuum, with polarizing glasses, with diffuse surfaces, with just 
about everything and no luck.  Well the project died after a few years and 
all the other companies that were trying it (about 4) ran into the same 
problem so all eventually had to quit.  Does anyone out there know if 
there's work being done on the problem?

The reason Im asking is that lately Ive seen some really strange 
transmitting surfaces, mainly CRT tube screens made out of millions of 
fiber-optic stands (about 1/8" long) packed side by side and melted (well, 
fused somehow) together.  The end effect is that the image from one side of 
the glass appears to be on the surface of the other side.  This means that 
the glass on you CRT appears to have zero thickness, a really cool effect.  
It also has a bunch of weird diffusion properties that I thought would work 
great for a laser TV. (if youre in WA and have a laser, give me a call. I 
can get a small sample of this stuff and try it out)  Has anyone out there 
seen a working laser TV system? 

PS: I saw something from MIT that does true 3D display by using a grid of 
piezo-electric and acousto-optic light modulators to generate a normal 
holographic interference pattern that can be recomputed on the fly (if you 
have a connection machine :) but thats something different, and far too 
complicated.

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