Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ncar!boulder!sunybcs!rutgers!gatech!bloom-beacon!mit-eddie!uw-beaver!fluke!strong 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 Distribution: na Organization: John Fluke Mfg. Co., Inc., Everett, WA Lines: 20 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)