How to Detect the Chandler and the Annual Wobble of the Earth with a Large Ring Laser Gyroscope

Abstract

We demonstrate a 16 m(2) helium-neon ring laser gyroscope with sufficient sensitivity and stability to directly detect the Chandler wobble of the rotating Earth. The successful detection of both the Chandler and the annual wobble is verified by comparing the time series of the ring laser measurements against the "C04 series" of Earth rotation data from the International Earth Rotation and Reference System Service.

A laser gyroscope system to detect the gravito-magnetic effect on Earth

“…can be achieved routinely [8,9]; Fig: 2 shows the typical Allan deviation of G, some relevant geophysical signal are also identified in the same picture; Fig: 2 indicates that the best precision is obtained integrating the signal for several hours, while for longer integration times the sensor resolution degrades. This is mostly due to external disturbances, such as atmospheric loading effects, diurnal and seasonal temperature variations, wind effects and hydrologic variations causing interactions with the rock and soil beneath the ring laser monument.…”

Precision cavity control for the stable operation of a large ring laser gyroscope

“…The sensitivity of the apparatus is enough to measure the polar motion, the tilt effects of the solid Earth tides and the length of day to approximately 1 part in a billion relative to the rate of rotation of the Earth (≈ 72 µrad/s) over one day of integration. By stabilizing the ring laser cavity against the effect of compression caused by atmospheric pressure variations and a slow drift in ambient temperature as the result of changing seasons, we have repeatedly achieved stable operations of the ring laser over several weeks, allowing to measure the low frequency contribution of the Annual and Chandler wobble to the instantaneous orientation of the gyroscope [2].…”

Absolute control of the scale factor in GP2 laser gyroscope: Toward a ground based detector of the lense-thirring effect

“…It is, actually, the most accurate ring-laser in the world. Thanks to its monolithic structure, where the mirrors are kept in position by optical contact on precisely tooled monolithic block of Zerodur, a glass with a "null" linear thermic expansion coefficient, G demonstrates a very high long-term stability that made possible the observation of very tiny geodetic effect, like polar motion and Chandler wobble [2]. A further increase in the angular resolution and a tri-axial gyro-system would, then, allow to reach 10 -14 rad/s; the sensitivity requested for measuring the Lense-Thirring General Relativity effect (also known as frame dragging) [3].…”