Re: [ARSCLIST] Optical disc "repair"

[Jerry Hartke <jhartke@xxxxxxxxxxxx>]

Very few suppliers of "repair" products or services use an independent
testing lab, such as ours, to validate their claims. I would expect
disappointing results.

Burnishing generates millions of microscopic scratches that act as a
diffraction grating and can degrade the laser beam. Burnishing also thins
the disc, which is undesirable because the distance from the entrance
surface to the information layer is carefully matched to the objective lens
in the drive. This lens predistorts the beam to compensate for the
refractive index of the polycarbonate layer, and the result is sensitive to
the thickness of the polycarbonate layer.

Best to replace a damaged disc or to make a copy while it is still readable.

Jerry
Media Sciences, Inc.

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx] On Behalf Of Marcos Sueiro Bal
> Sent: Thursday, February 07, 2008 11:02 AM
> To: ARSCLIST@xxxxxxxxxxxxxxxx
> Subject: [ARSCLIST] Optical disc "repair"
> 
> On my way to work this morning I was intrigued by a poster in the local
> game shop advertising CD and DVD "mail-in" repair. I went to the web
> site listed. Take a look around; it is fascinating, among other things
> because it is directed towards dealers selling the process.
> 
> http://www.azuradisc.com
> 
> I have heard at least one expert in optical media state that all of this
> burnishing systems are actually damaging the polycarbonate layer and are
> harmful in the long run, but I wonder if there are any papers showing
> any reduction of errors after this kind of process (good luck finding
> links to such a paper in the web site above). If so, could process like
> this one be compared to, say, baking of tapes? In other words, "get the
> data to another medium while you can"? (But note that this is not what
> they advertise in the web site; they advertise actual repair of the
> disc... it will be like new!)
> 
> There are accessories sold by this company (e.g. foam for your jewel
> case?!?) that make me suspicious, but I am not ready to condemn their
> whole process yet. I am curious to hear reactions or comments from other
> posters.
> 
> Cheers,
> 
> Marcos Sueiro
> Columbia University