Half a croissant, on a plate, with a sign in front of it saying '50c'
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CD Spin Off

move the laser, not the disc
(+3, -3)
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I'm sure this has been done before, but can someone remind my why the compact disc has to spin to be read? In the good old days, I'm sure the laser pickup wasn't sophisticated enough to read refracted light, but surely nowadays the laser could read its way around the disc, whilst the disc remains stationary ? thus (probably) improving battery life and noise from CD readers.
neilp, Dec 06 2004


       It seems to me like it would be much more difficult and energy-hungry to spin a laser than it would be to spin a disc. The disc wouldn't be effected by centripetal force, but the laser head probably would.
contracts, Dec 06 2004

       thansk [contracts], I wasn't actually thinking of spinning the laser, instead having it located centrally at the axis of the disc and pivoting round (like one of those old Searchlights they used to have outside cinemas).
neilp, Dec 06 2004

       Have the laser point at a mirror that moves. This is regularly done in laser printers albeit in a linear fashion. DLP projectors use very small "solid state" mirrors which would be ideal for this application if they can be made to move on two axes. With such a system, one might be better off with square CDs/DVDs...
phoenix, Dec 06 2004

       further to what phoenix said: have the laser point at a single mirror that moves and reflects to a parabolic mirror that reflects to the CD... this way the laser beam is always perpendicular to the CD.
xaviergisz, Dec 06 2004

       What if the CD remains in one place, and we spin the entire planet beneath it ?
normzone, Dec 06 2004

       I would not be surprised if some companies like OnTrack Data Systems have equipment that does essentially this. Such equipment would probably be very slow, but if someone was willing to pay $50,000 for a best-effort attempt to recover data from a broken CD it could probably be useful (trying to glue and spin a broken CD would, of course, risk breaking it more).
supercat, Dec 07 2004


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