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From: jerry@oliveb.UUCP (Jerry Aguirre)
Newsgroups: net.physics
Subject: Re: Quartz Gyroscopes in Space? - (nf)
Message-ID: <153@oliveb.UUCP>
Date: Fri, 31-Aug-84 14:27:43 EDT
Article-I.D.: oliveb.153
Posted: Fri Aug 31 14:27:43 1984
Date-Received: Mon, 3-Sep-84 09:20:12 EDT
References: <10800007@uiucdcsb.UUCP> <1403@pur-phy.UUCP>
Organization: Olivetti ATC, Cupertino, Ca
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It's all done with mirrors!  Really!

I was quite intrigued by the concept of a no-moving-parts gyroscope so
when an explanation appeared I studied it until I think I understood
it.  The basic arrangement is to have two light beams traveling in
opposite directions and reflected or refracted in a roughly circular
path.  The example used a triangle formed by three mirrors.

                      mirror->  -------
				  / \
                                /     \                      
                          \   /         \   /          
                  mirror->  \ ___________ /  <-mirror 
                              \         /            

The light is supplied by a laser and is split into two beams, one of
which travels clockwise, and the other which travels counter-
clockwise.  Part of each beam is tapped off and the frequency of the
two beams is compared.  Any rotation of the gyroscope will cause a
doppler effect and therefor a change in the frequency of the two
beams.

I have also read about a design which uses a fiber-optic cable wound on
a spool.  That design offers greater mechanical ruggedness.