Fosrem: Fibre-optic system for rotational events and phenomena monitoring: Construction, investigation and area of application

Abstract

This paper reviews our expertise with construction, investigation and simulation of the fibre optic interferometric device named FOSREM (Fibre-Optic System for Rotational Events and Phenomena Monitoring). The presented device was designed for a direct monitoring of rotational components emitted during seismic events as well as existing in irregular and complex structures. The construction of the FOSREM utilizes the Sagnac fibre interferometer in a minimum optical gyro configuration. This approach causes that FOSREM is complete insensitivity to linear motions, and it enables to measure directly the rotational components. In order to make FOSREM mobile and autonomous device we were focused on decreasing size to the 36Χ36Χ16 cm dimension and implementing special FORS – Telemetric Server which enables to control FOSREM remotely via Internet. The laboratory investigation of our system indicated that it keeps the theoretical sensitivity equal to 2·10_8 rad/s/Hz1/2 and accuracy no less than 6·10_9–5·10_5 rad/s in a frequency band from 0 Hz to the upper frequency between 2.56 and 328.12 Hz, respectively. FOSREM protects linear changes of sensitivity in the above detection frequency bandpass and has the maximum values of rotation rate possible to record without “overshoot” equal to 10 rad/s due to an innovative electronic system.