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From: strong@tc.fluke.COM (Norm Strong)
Newsgroups: sci.electronics
Subject: Re: CD Player Questions
Message-ID: <3999@fluke.COM>
Date: 6 Jun 88 19:21:14 GMT
References: <3385@ncrcae.Columbia.NCR.COM> <3608@briar.Philips.Com>
Sender: news@tc.fluke.COM
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Organization: John Fluke Mfg. Co., Inc., Everett, WA
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In article <3608@briar.Philips.Com> drg@philabs.Philips.Com (Don Gentner) writes:
}In article <3385@ncrcae.Columbia.NCR.COM>, wte@ncrcae.Columbia.NCR.COM (Bill Eason) writes:
}> When I asked about the number of lasers tracking (something most ads hype),
}> the salesman told me that CD player makers "...found that the number of lasers
}> really didn't make any difference in how well the disc was tracked."  By
}> the time that sentence got past my ears, it sounded more like "We don't carry
}> any models with that feature."  What do netters think?
}
}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" 
}--
Quite right.  The advantages of a 3-beam pickup are that it doesn't violate
the patents owned by Philips of Netherlands.
-- 

Norm   (strong@tc.fluke.com)