Reviews of Modern Physics, Vol. 57, No. 1, January 1985.This paper presents a review of both active and passive ring laser devices. The operating principles of the ring laser are developed and discussed, with special emphasis given to the problems associated with the achievement of greater sensitivity and stability. First-principle treatments of the nature of quantum noise in the ring laser gyro and various methods designed to avoid low-rotation-rate lock-in are presented. Descriptions of state-of-the-art devices and current and proposed applications (including a proposed test of metric theories of gravity using a passive cavity ring laser) are given.Contents:
Introduction.
Sagnac effect.
Passive ring resonator gyros.
Conventional (two-mode) active laser gyro.
Multimode devices.
Noise in optical rotation sensors.
Acknowledgment.
Appendix: Derivation of wave equation.
References.
