Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!aplcen!uakari.primate.wisc.edu!sdd.hp.com!decwrl!sgi!shinobu!odin!odin.corp.sgi.com!tomw From: tomw@orac.esd.sgi.com (Tom Weinstein) Newsgroups: comp.arch Subject: Re: Data Storage density questions Message-ID: Date: 6 Aug 90 18:45:23 GMT References: <2635@mindlink.UUCP> <10048@pt.cs.cmu.edu> <1990Jul30.231835.13898@diku.dk> <10055@pt.cs.cmu.edu> Sender: news@odin.corp.sgi.com Reply-To: tomw@esd.sgi.com Organization: Silicon Graphics Inc. Lines: 40 In-reply-to: lindsay@MATHOM.GANDALF.CS.CMU.EDU's message of 31 Jul 90 16:05:10 GMT In article <10055@pt.cs.cmu.edu>, lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: > It used to be that one scanned a laser beam by pointing a fixed beam > at a rotating mirror - this was the technology inside laser printers. > Supermarket barcode readers used a rotating film, with a hologram > printed on it. > There used to be a lot of hope that we would find less mechanical > solutions. I'm out of date on this subject - I stopped reading Laser > Focus &c - but I'm not aware of a relevant breakthrough. I think > that the problem with limited angular effects was also the limited > angular resolution: that is, not enough bits in the seekable address > space. If that's still true, then lens arrangements only fix the > less-important limitation. > Correction are welcome. Does anyone know how the latest laser > printers work? > -- > Don D.C.Lindsay I read a paper a couple months ago about something they are doing at NASA. They have a whole series of electrode fingers over a strip electro-optical medium. The fingers are oriented at 45 degrees to the axis of the strip. By applying a potential difference between some of the electrodes and an anode on the other side, they can cause the medium to reflect. Like a dielectric mirror, it's because of the spacing of layers of different indices of refraction. You can get quite good resolution this way. The application they were developing for was laser printers, so they fed it through a diverging lens to convert the spatial displacement to angular displacement. It sounds like this technique could be used for disk drives too. Don't expect this out in printers any time soon, though. They still have a patent application pending last I heard. -- Tom Weinstein Silicon Graphics, Inc., Entry Systems Division, Window Systems tomw@orac.esd.sgi.com Any opinions expressed above are mine, not sgi's.