Laser gyroscopes for very high sensitive applications

We present a summary of the recent results obtained with the "G-Pisa" laser gyroscope prototype in the field of rotational metrology. The experimental apparatus consists in an He-Ne laser having a planar square cavity 1.35 m in side that can be operated both in the vertical and in the horizontal plane. For about one year, the ring laser has been utilized by the Virgo gravitational wave interferometer with the aim of estimating and monitoring the local rotational noise which is degrading the performances of its inertial suspensions. Results in the field of environmental monitoring for the improvement of the suspension control as well as the results in the field of rotational seismology are presented. In the last part of the paper we present some considerations about the possibility of performing a ground-based General Relativity test using an array of ring lasers.