Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton!23r@sage.cc.purdue.edu
From: 23r@sage.cc.purdue.edu (John Dormer)
Newsgroups: sci.virtual-worlds
Subject: Re: optical gyros
Message-ID: <11836@milton.u.washington.edu>
Date: 28 Nov 90 06:58:10 GMT
References: <11727@milton.u.washington.edu>
Sender: hlab@milton.u.washington.edu
Organization: occasional on alternate Tuesdays
Lines: 29
Approved: hitl@hardy.u.washington.edu




  I recall from a couple years back, when I was very interested in laser
devices, that Hughes Aircraft had made optical (laser-ring) gyroscopes. The
ones for military aircraft could detect >extremely< small rotations...measured
in degrees per minute, and they were decimal numbers to boot.
  I don't know if anyone has made smaller versions of this technology, but it
should be feasable. The Hughes ring was about $200k I think...a bit expensive,
but I remember reading somewhere about a company who had sucessfully made a
solid version of the ring-gyroscope (Hughes used mirrors on a stout frame
about 10" across [from the photos]), which used beveled, mirrored faces on
the outside of some kind of crystal material (optical glass probably). The
availability of IR laser diodes should bring the price down quite a bit. And
because these devices use phase to tell which direction (combination of
directions) the ring has moved, you need only one to detect any twisiting
motion. I don't know how well they fare as acceleratometors, but they should
do allright. The most expensive part of this would still be the detector
optics, and I don't know enough about that part to make an educated guess on
how much it would cost. The whole package should cost less than the original
Hughes device (I'd hope! 8), but more than $10,000 most likely (at first).
Holographic lenses could shave the cost of the detector again, but this is
also something beyond me. These lenses could be produced cheaply in quantity
with decent quality control. Maybe we're talking $2000 for this device in
production quantities of 1000 per lot, who knows.

        another brilliant idea?
        John Dormer
        dormer@medusa.cs.purdue.edu