🚀 go-pugleaf

In article <3608@briar.Philips.Com> drg@philabs.Philips.Com (Don Gentner) writes:
>As far as I know, all CD players have only one laser.  In 3-beam players,
>the laser beam is split into 3 beam before reflecting off the disc.  In single-
>beam players, the beam is split after reflecting off the disc.  In either
>case one signal is used for data and the other two beams are used for 
>tracking and focus correction.  Both systems work, but the single beam system
>has the advantage of simpler design and fewer parts to get out of alignment.
>I don't know of any advantage of a 3-beam system, except "ad hype" 
>--

How do you manage to correct the tracking and focusing with 1 laser
beam??  It would seem that if you split the laser AFTER it reflects
off the disc you are carrying much less critical info for 
correcting purposes...

Andrea Severino, GOULD-CSD (San Diego Division) (619)485-0910 xt. 272 
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