Here is a link to the original article:
"Utilizing 3-D digital laser microscopy to image damaged optical media."
By Greg Gogolin, James Jones, and Derek Brower
On 3/27/15 10:33 AM, Steven Smolian wrote:
> 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
> Ampex Mailing List
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