This is from the Ampex list.  I thought some of the ARSC and MLA readership
would be interested as well.

Steve Smolian 

-----Original Message-----
From: Ampex [mailto:[log in to unmask]] On Behalf Of Bill Ruck
Sent: Friday, March 27, 2015 12:51 AM
To: Ampex Mailing List
Subject: [AMPEX] Survival

Saw this today in the March 2015 issue of Laser Focus World.   (Yes, 
I do read strange magazines.)

Olympus microscope recovers data from damaged optical media

Designed for nanometer-level imaging and 3D measurements, the LEXT OLS4000
laser-scanning confocal microscope from Olympus (Center Valley, PA) can
provide both visual and height maps of damaged CD and DVD optical media (or
acute-angled specimens) and recover data from that media using custom
algorithms.  With a 405 nm wavelength source, the LEXT OLS4000 has a
magnification range from 108X to 17,280X and dedicated objective lenses with
high numerical apertures.

To obtain usable information from damaged optical media (both
factory-pressed and home-burned CDs and DVDs), a highly magnified image of
the damaged media is created and a region of consecutive dots and dashes is
selected.  Although the dots and dashes appear to form concentric circles,
they actually form a spiral, so there are no beginnings and endings to the
apparent tracks.  Each dot and dash is then quantitatively measured.

Next, the encoding algorithm used to convert the original data into dots and
dashes is reversed.  (There are only a handful of encoding algorithms in
wide use, and most of these are publicly
available.)  Even if severe data impact has occurred (significant scratches,
chemical alterations, surface destriction, or even a disc broken into
multiple pieces), it is still possible to adjust the algorithms to recover
data based on measurements obtained by the OLS4000.

So it seems to me that the guys now recovering audio from strips coated with
iron rust need to invest in something like this for optical media.

Bill Ruck
San Francisco

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