Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!uakari.primate.wisc.edu!polyslo!dorourke
From: dorourke@polyslo.CalPoly.EDU (David M. O'Rourke)
Newsgroups: comp.sys.mac
Subject: Re: Erasable optical drives
Keywords: Erasable optical disk storage
Message-ID: <1989Oct11.233148.19398@polyslo.CalPoly.EDU>
Date: 11 Oct 89 23:31:48 GMT
References: <819@mit-amt.MEDIA.MIT.EDU>
Reply-To: dorourke@polyslo.CalPoly.EDU (David M. O'Rourke)
Distribution: usa
Organization: Cal Poly State University -- San Luis Obispo
Lines: 25

mjkobb@media-lab.media.mit.edu (Michael J Kobb) writes:
>  My friend maintains that the drive is written to with the laser and the
>magnet, but that it is read exclusively with the laser, depending on the
>altered magnetic field of the molecules to either reflect or scatter the laser
>beam.
>
>  Question:  which, if either, of us is correct?

  I'm no expert on this subject, but my file structures teacher did have us
read a very interesting article on the subject.

  It's my understanding that the poster's description of how the disk is
written to is essentially correct.  The disk is read by bouncing a laser off
of one of the "bit's" on the disk, and depending on how that "bit" was
polarized you can read the effect on the laser.  It seems that you can
read how a laser is polarized, and the magnetic field in the bit area will
affect the laser's polarization, which is read, and therefore you can
encode 0's & 1's on the different polarizations.

  Hope this helps, I'm sure if I'm wrong people will notify the net :-)
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David M. O'Rourke____________________|_____________dorourke@polyslo.calpoly.edu
| Graduating in March of 1990, with a BS in Computer Science & need a Job.    |
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