Re: [ARSCLIST] Optical Groove Digitization

[Samuel Brylawski <sbry@xxxxxxx>]

I think that we've been negligent in not pointing out earlier the work of
Carl Haber and Vitaliy Fadeyev at the Lawrence Berkeley Lab. They made a
presentation at the Library of Congress this June. They are exploring both
2-D and 3-D mapping. A PowerPoint presentation and a paper submitted to
AES can be found at:


http://www-cdf.lbl.gov/~av/

Sam B.



On Wed, 24 Sep 2003, Jon Noring wrote:

> Peter Copeland wrote:
>
> >     I agree, and must add another dimension to solving this problem - my
> > twopennyworth! The only practical way to do a three-dimensional map of a
> > groove (whether hill-and-dale, lateral, or stereo) is to use a test probe
> > controlled by a digital device of some sort. However, there is no
> > anti-aliassing filter for the data. Therefore the wanted sound is going to
> > be corrupted by an enormous amount of aliassing, and ultrasonic components
> > will become "folded down" into the audio spectrum.
> >     The fundamental idea is a good one, but I'm afraid I cannot see how to
> > get around this problem - *except* by playing the groove with a stylus and
> > having an anti-aliassing filter *before* the result(s) are digitised. If
> > anyone can think of how to conquer that, it *would* be a good idea!
>
> I agree with you that if the fineness of the 3-d topographic data is
> insufficient (it is too course), then it will not accurately enough
> represent the contours of the groove walls. That's why I commented
> that the amount of data needed to be gathered for a single disk is
> very large (I did a back of the envelope calculation and came up
> with well over a gig of 3-d sample points -- a lot of data, but by
> today's standards is not that onerous.)
>
> The idea is to sample enough points that it would even be possible, if
> one has precise enough stereo lithography equipment, to create a new
> disk from the data and be able to play it traditionally!
>
> Now, to gather the data, it would probably be some sort of
> triangulated laser system which can precisely measure the height of
> any spot on a record. As I noted before, it would not surprise me if
> such equipment already exists (for precise contouring of rough
> surfaces for research purposes). If it doesn't exist, I'm pretty sure
> it could be built.
>
> If anyone here in a university or archive research organization is
> interested in pursuing the conceptual research into this idea, I'd be
> willing to assist -- I do have credentials having worked as a staff
> scientist at Lawrence Berkeley Laboratory and mechanical engineer at
> Lawrence Livermore Laboratory, with a solar energy stint at Sandia
> Labs.
>
> Jon Noring
>