An Overview Of Passive Optical "Gyros"

Abstract

An Overview of Passive Optical GyrosShaoul EzekielResearch Laboratory of ElectronicsMassachusetts Institute of Technology, Cambridge, MA 02139AbstractA brief and simplified overview of optical gyroscopes is presented with emphasis onrecent developments in passive approaches.Why the Interest in Rotation Sensors?The measurement of rotation is of considerable interest in a number of areas. Forexample, inertial navigation systems as used in aircraft and spacecraft depend criticallyon accurate inertial rotation sensors. The allowable errors in rotation sensor performancedepend on the particular application. Typical requirements for aircraft navigation lie be-tween 0.01 and 0.001 degrees /hour. In terms of earth rotation rate QE = 15 degrees /hourthis becomes 10 -3 to l0 -4 QE. A number of other applications of rotation sensors existsuch as surveying where the accurate determination of azimuth and geodetic latitude isimportant [1]. In this case performance of 10 -6 QE or better is needed. Geophysics appli-cations include the determination of astronomical latitude, and the monitoring of polarmotion caused by wobble, rotation, precession and wandering effects [1]. A highly preciserotation sensor may be used to measure any changes in the length of the day and to detecttorsional oscillations in the earth caused by earthquakes. Finally, ultraprecise sensorsmay find applications in relativity related experiments such as the determination of thepreferred frame, dragging of inertial frames, etc.