An argon ion ring laser as a gyroscope

As a prototype gyroscope for a precision measurement of the Earth's rotation Ω_E, we set up an argon ion ring laser with an area of 1.4 m². Different cavity geometries were tested in order to achieve a cancellation of the effect of the plasma flow. In a set-up with two laser tubes of the same type facing towards opposite directions, a stability of the beat frequency of 2-3 Ω_E was measured. In a configuration with a double transition of the laser beam through the tube, the lock-in threshold was too high for the Earth's rotation to be measured, however, no effect of the plasma flow was observed.