🚀 go-pugleaf

No flame intended.

When you write, the large laser heats a spot on the disk and the
magnet sets the orientation of light-rotation of the material.
The small laser is not used in the write process.  Because it 
needs both a laser and a magnet, the mechanism is called MO
(Magneto-Optical).  Of course, the polarity of the magnet is
controlled by the computer.

When you read, the small laser shines polorized light on the spot
and the reflected light is rotated one way to represent a "1" and
the other way to represent a "0".

Because the lasers and the magnet never touch the disk surface,
the media can last very long time.  For some other reasons, the
shelf life of the media is also  very long (30 years as opposed
to about 10 years for magnetic media).

Cheers!

Jie

In article <48a7qm$s20@conch.aa.msen.com>, Mike Pelletier
<mpelletier@ofgw.ntt.com> writes:
> In article <47s9ou$m53@shellx.best.com>, Mike Iimura <miimura@best.com>
> wrote:
> >
> >So what are you saying??  Do you have to flip the cartridge to read the
> >rest of the disc??
> >
> >- Mike Iimura
> >  miimura@best.com
> 
> That's correct -- that's how all MO drives operate as far as I know.  A 
> 1.3GB MO is two 650MB sides.
> 
> The problem lies in the way MO is written, or so I've been told -- a
> higher-intensity laser beam actually heats up a small section of the disk
> making its crystal structure somewhat malleable.  Then a second, lower
> intensity laser, in the presence of a changing magnetic field, changes the
> optical polarization of the medium before it cools.  When it cools, the
> polarization can be read by a low-intensity laser beam.  Apparently 
> writing and reading both sides of the disk either isn't possible or is 
> too technically challenging to be practical yet, due to this method of data 
> transfer.
> 
> 	-Mike Pelletier.
>