Path: utzoo!attcan!uunet!snorkelwacker!tut.cis.ohio-state.edu!pt.cs.cmu.edu!MATHOM.GANDALF.CS.CMU.EDU!lindsay
From: lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay)
Newsgroups: comp.arch
Subject: Re: Data Storage density questions
Message-ID: <10055@pt.cs.cmu.edu>
Date: 31 Jul 90 16:05:10 GMT
References: <2635@mindlink.UUCP> <10048@pt.cs.cmu.edu> <1990Jul30.231835.13898@diku.dk>
Organization: Carnegie-Mellon University, CS/RI
Lines: 29

In article <1990Jul30.231835.13898@diku.dk> njk@diku.dk 
	(Niels J|rgen Kruse) writes:
>>Specifically, it would be nice if we scanned a laser beam over the
>>media, rather than rotated the media.  Or, at least, did the "head"
>>movement that way.  There was hope for this sort of thing, a decade
>>ago, and somehow it never happened.  I believe that the best spatial
>>modulators had very limited angular effect (...)

>Would you care to elaborate on this?  What kind of spatial modulators?
>Even if the angular effect is small, wouldn't it be a simple
>matter to increase it with some sort of lens arrangement?

It used to be that one scanned a laser beam by pointing a fixed beam
at a rotating mirror - this was the technology inside laser printers.
Supermarket barcode readers used a rotating film, with a hologram
printed on it.

There used to be a lot of hope that we would find less mechanical
solutions.  I'm out of date on this subject - I stopped reading Laser
Focus &c - but I'm not aware of a relevant breakthrough.  I think
that the problem with limited angular effects was also the limited
angular resolution: that is, not enough bits in the seekable address
space.  If that's still true, then lens arrangements only fix the
less-important limitation.

Correction are welcome.  Does anyone know how the latest laser
printers work?
-- 
Don		D.C.Lindsay