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Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!wmartin
From: wmartin@brl-tgr.ARPA (Will Martin )
Newsgroups: net.audio
Subject: Re: Vinyl vs. CD recordings
Message-ID: <5356@brl-tgr.ARPA>
Date: Wed, 17-Oct-84 09:50:14 EDT
Article-I.D.: brl-tgr.5356
Posted: Wed Oct 17 09:50:14 1984
Date-Received: Thu, 18-Oct-84 19:04:58 EDT
References: <3050@watcgl.UUCP> <4100001@hp-lsd.UUCP>
Organization: Ballistic Research Lab
Lines: 23

> A laser pickup cartridge was developed several years ago.  I dimly recall
> reading about it in one of the Popular*-type magazines.  I wish I could
> remember a reference.
> 
> 	(or did they use focused LED's???)
> 
> 			--Paul Bame
> 			hplabs!hp-lsd!paul

I am rather doubtful that an actual "laser" cartridge has yet been
developed; however, there was a Japanese (I believe Panasonic/Matsushita)
photoelectric or "light-beam" cartridge some years back. It came in a
special spherical housing, like a big aluminum bubble on the end of the
tonearm. I think the cantilever moved a mirror which modulated a light
beam reflected on a photcell receptor of some form. The idea was to
minimize the mass moved by the stylus, as usual.

In any case, this (and any "laser cartridge") still is a needle-in-a-groove
contact system; what I had posted a while ago about laser playback of
existing vinyl discs was a postulate about a non-contact system, where
only the laser light touched the disc.

Will