Preliminary Results from a Large Ring Laser Gyroscope for Fundamental Physics and Geophysics

摘要

Preliminary results from a new-generation ring laser gyroscope C-II are presented. C-II has a square optical path with side 1m. One difference with the earlier C-I laser - and similarity to an aircraft gyro - is its monolithic construction. It is housed 30m underground in a New Zealand military bunker. The measured ringdown time of 0.20ms corresponds to a quality factor 6.0×10{sup}(11) and a finesse 9.4×10{sup}4. For the observed exit beam power of 10pW, this gives an angular rotation sensitivity 4×10{sup}(-9)rad/s/sqrt(Hz). C-II performance limits therefore rival those of Sagnac matter-wave gyroscopes (2×10{sup}(-8)rad/s/sqrt(Hz), Gustavson et al., Phys. Rev. Lett. 78, 2046-9 (1997)). This also corresponds to a quantum noise line width of 220 microhertz, consistent with that observed (172 microhertz) in the direct spectrum and with the coefficient of inverse time in an Allan variance plot.