High sensitivity tool for geophysical applications: a geometrically locked ring laser gyroscope.

Area of Science:

• Geophysics
• Seismology
• Optical Engineering

Background:

• Rotational seismology requires highly sensitive instruments to detect Earth's subtle rotational motions.
• Traditional seismometers primarily measure linear ground motion, necessitating specialized tools for rotational components.

Purpose of the Study:

• To evaluate the performance of a middle-sized ring laser gyroscope (RLG) as a sensitive instrument for rotational seismology.
• To assess the RLG's robustness and stability in a noisy, real-world environment.

Main Methods:

• Utilized a square cavity (1.60x1.60m²) ring laser gyroscope positioned orthogonal to Earth's rotation.
• Employed Fabry-Perot optical cavities locked to a reference laser for sensing.
• Operated the RLG using a simple locking circuit for continuous data acquisition.

Main Results:

• The RLG operated continuously and robustly for 14 days.
• Achieved long-term stability of approximately 3 nanorad/s.
• Demonstrated short-term sensitivity close to 2 nanorad/s·Hz⁻¹/², meeting seismic requirements.

Conclusions:

• A middle-sized RLG is a viable and sensitive instrument for rotational seismology.
• The RLG's performance is robust despite operating in a noisy urban laboratory environment.
• The demonstrated stability and sensitivity are promising for future seismic monitoring applications.