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Re: blank DVDs no recognized, other media OK

On Tuesday 29 August 2006 15:05, Matthias Julius wrote:
> Lennart Sorensen <lsorense@csclub.uwaterloo.ca> writes:
> > What model of drive?  Any chance the DVD laser is toast on the drive,
> > but the CD laser is OK?  They are different lasers running different
> > wavelength of light.
> Are you sure?  I thought they both use red lasers.

CDs use IR light (800nm).  DVDs use visible red light (635nm).  Although the 
shorter wavelength laser ought to be able to read the larger pits and lands 
of CDs, I don't think this is done in practice.  If you look at a portable 
DVD/CD player  (where you can easily see the innards),  you will clearly see 
two separate laser lenses.

You could check the drive by substitution in a known-good machine, or by 
mounting a LiveCD of a different distro, eg. Slax 
(http://slax.linux-live.org) or Knoppix 


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