AFORS Autonomous Fibre-Optic Rotational Seismograph: design and application

We outline the research leading to development of the Autonomous Fibre-Optic Rotational Seismograph (AFORS) and describe the final version of the instrument. The instrument with linear changes of sensitivity keeps accuracy from 5.1 x 10minus9 to 5.5 x 10minus8 rad/s in the detection bandpass 1.66-212.30 Hz; it is designed for a direct measurement of rotational components emitted during seismic events. The presented system is based on the optical part of the fibre optic gyro construction where a special autonomous signal processing unit (ASPU) optimizes its operation for the measurement of rotation motions instead of the angular changes. The application of a newly designed telemetric system based on the Internet allows for a remote system control, as shown in an example of the system's operation in Ksiaz (Poland) seismological observatory.