A 1.82 m2 ring laser gyroscope for nano-rotational motion sensing

Abstract

We present a fully active-controlled He-Ne ring laser gyroscope operating in square cavity 1.35 m in side. The apparatus is designed to provide a very low mechanical and thermal drift of the ring cavity geometry and is conceived to be operative in two different orientations of the laser plane, in order to detect rotations around the vertical or the horizontal direction. Since June 2010 the system is active inside the Virgo interferometer central area with the aim of performing high sensitivity measurements of environmental rotational noise. So far, continuous unattended operation of the gyroscope has been longer than 30 days. The main characteristics of the laser, the active remote-controlled stabilization systems and the data acquisition techniques are presented. An off-line data processing, supported by a simple model of the sensor, is shown to improve the effective long term stability. A rotational sensitivity at the level of 10 −8 rad/ √ Hz below 1 Hz, very close to the required specification for the improvement of the Virgo suspension control system, is demonstrated for the configuration where the laser plane is horizontal.

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

“…In the INFN laboratory in Pisa a laser gyroscope of relative small dimension (1.35 m of side) has been developed [6,7]. This apparatus is presently located in the Gran Sasso underground laboratories of INFN, in order to test whether the site is suitable to locate the GINGER (Gyroscopes IN General Relativity) experiment.…”

A high-precision mechanical absolute-rotation sensor

“…6,7 They are traditionally run horizontally to sense rotation about the vertical axis, but can be mounted vertically to sense rotation about a horizontal axis. 8,9 Our design offers a simpler and more compact alternative. For comparison, it has roughly an order of magnitude better angle sensitivity than the horizontal-axis ring-laser gyroscope described in Belfi et al 9 between 10 to 100 mHz.…”

“…8,9 Our design offers a simpler and more compact alternative. For comparison, it has roughly an order of magnitude better angle sensitivity than the horizontal-axis ring-laser gyroscope described in Belfi et al 9 between 10 to 100 mHz. In this frequency band, our sensor has comparable sensitivity to the angle sensitivity of C-II: a vertical-axis meter-scale monolithic laser ring gyro 6,7 and its sensitivity is surpassed by roughly an order of magnitude by the horizontal-axis 3.5 meter-square G-0 ring-laser gyro.…”

Planar angle metrology: G-LAS, the INRIM - INFN ring laser goniometer

“…This project exploits the large expertise on RL gyroscope acquired in the recent years by the group operating at the section of Pisa of INFN and at the Pisa University Department of Physics [3,4] with the purpose of building a gyroscope having the very high sensitivity that needs for detecting in a terrestrial laboratory the thin effect foreseen by the general relativity equations, due to the distortion of the space-time metrics induced by the rotating Earth mass (the so called Lense-Thirring effect), which is expected to give a correction of the order of 1 ppb over the Earth rotation speed [5,6].…”