Passive, free-space heterodyne laser gyroscope
Laser gyroscopes making use of the Sagnac effect have been used as highly accurate rotation sensors for many years. First used in aerospace and defense applications, these devices have more recently been used for precision seismology and in other research settings. In particular, mid-sized (~1 m-scale) laser gyros have been under development as tilt sensors to augment the adaptive active seismic isolation systems in terrestrial interferometric gravitational wave detectors. The most prevalent design is the 'active' gyroscope, in which the optical ring cavity used to measure the Sagnac degeneracy breaking is itself a laser resonator. In this article, we describe another topology: a 'passive' gyroscope, in which the sensing cavity is not itself a laser but is instead tracked using external laser beams. While subject to its own limitations, this design is free from the deleterious lock-in effects observed in active systems, and has the advantage that it can be constructed using commercially available components. We demonstrate that our device achieves comparable sensitivity to those of similarly sized active laser gyroscopes.
© 2016 IOP Publishing Ltd. Received 23 September 2015, revised 18 November 2015. Accepted for publication 4 December 2015. Published 11 January 2016. The authors gratefully acknowledge the support of the National Science Foundation and the LIGO Laboratory, operating under cooperative Agreement No. PHY-0757058. We would also like to thank Shaoul Ezekiel, as well as Brian Lantz and other members of the LIGO Scientific Collaboration Suspensions Working Group, for early suggestions. We further express gratitude to the Caltech SURF program, and in particular to Michelle Stephens, Jenna Walrath, and Zoe Masters for their contributions as summer fellows. Finally, we are grateful for help and advice from Denis Martynov, Tara Chalermsongsak, Frank Seifert, Jenne Driggers, David Yeaton-Massey, and Steve Vass.
Submitted - 1508.07025v1.pdf