The development of a sensor model for Large Ring Lasers and their application in seismic studies

The general ring laser operation model is adopted for the large gyroscopes C-II and G. An extended set of auxiliary sensors information is used for the long time period data modeling and ring laser behavior analysis with respect to the ideal case. Both instrumental errors and orientational effects are estimated and compensated where possible. The instrumental stability improved approximately for one order of magnitude for timeseries with duration of up to 70 days. This makes small periodic signals of geophysical interest accessible in the presence of instrumental drift. Basic considerations for the application of ring laser in seismology are presented. The design principles of the GEOsensor, a rotational measurement system for seismology, are demonstrated along with a comparison of rotational seismograms taken from different ring lasers as a proof of concept. The various Sagnac frequency extraction methods are analyzed and compared. As a result the key technology for obtaining rotational seismograms developed. The appropriate data acquisition approach has been chosen with respect to the requirements in seismology and is described. The procedures of the GEOsensor ring laser component installation, beam path alignment and experimental setup are described. The comparison of the GEOsensor data with rotational signal from G and linear signal from standard seismometer are provided. The value of the GEOsensor as a complex stand-alone seismological station is discussed.