G-LAS: a ring laser gyroscope for high accuracy angle measurements

Angle measurements at the uncertainty level of tens of nanoradian are needed in many applications, from precision mechanical industry to astronomy, geodesy and experimental physics. Nowadays state of the art instruments to measure large angles, i.e. angular encoders, can achieve resolutions to the nanoradian level, but the traceability to the angle unit is not guaranteed at the same level of uncertainty. A novel ring laser gyroscope has been designed and built in a joint research project between INRIM and INFN. The device is based on a gyroscope 50 cm in side-length mounted on a precision rotating table. Exploiting the Sagnac effect, it will behave as an ideal angular encoder capable of generating and measuring angles over the full circle interval with a target accuracy of the order of 10 nrad.