Invited Review Article: Large ring lasers for rotation sensing

Abstract

Over the last two decades a series of large ring laser gyroscopes have been built having an unparalleled scale factor. These upscaled devices have improved the sensitivity and stability for rotation rate measurements by six orders of magnitude when compared to previous commercial developments. This progress has made possible entirely new applications of ring laser gyroscopes in the fields of geophysics, geodesy, and seismology. Ring lasers are currently the only viable measurement technology, which is directly referenced to the instantaneous rotation axis of the Earth. The sensor technology is rapidly developing. This is evidenced by the first experimentally viable proposals to make terrestrial tests of general relativistic effects such as the frame dragging of the rotating Earth.

A high-precision mechanical absolute-rotation sensor

“…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. 7 …”

“…5 Large ring-laser gyroscopes are the traditional rotation sensors used in this field. 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.…”

Hands on GINGER: Seismic Wave measurement

“…A ring laser converts very small time differences in measurable frequency differences. Even though the principle of operation of a ring laser is quite simple, they can reach a sensitivity as high as 1.2 × 10 −11 rad/(s √ Hz), resolving an angular speed of about 1.5 × 10 −13 rad/s in 4 hours integration time [1]. The underlying principle of working of a ring laser is the Sagnac effect, which is here outlined following a classical interpretation.…”

Nonlinear fiber gyroscope for quantum metrology

“…In this work we focus on the quantum limits to the resolution achievable in gyroscopes as good candidates to exploit the benefits of nonlinear detection, paying special attention to quantum characteristics exclusive of this interferometer [17]. We will focus on the case when the gyroscope is illuminated by practical field states, i.e., that can be generated in practice and are robust against imperfections, such as coherent and quadrature squeezed states.…”