Liquid-Damped Fiber Laser Accelerometer: Theory and Experiment

Liquid-damped fiber laser accelerometers (LD-FLAs) are promising to be used in some oil-filled and high pressure resistance instruments, such as ocean bottom seismographs and deep-well petroleum seismic geophones. A kind of LD-FLA structure, of which damping liquid could be easily changed, was designed to study its damping characteristic. The principles of an LD-FLA were analyzed comparing with a common FLA, which found that liquid damper could produce additional liquid pressures in vibration so that not only damping response of resonance peak but sensitivity could be changed at the same time. Four double diaphragm-based LD-FLAs were manufactured and experiments under three kinds of damping liquids were carried out. The experimental results are close to the calculated values and show that the average sensitivity of designed LD-FLAs is ~1.3 dB lower than that of air-filled FLAs and the working frequency band turns a little broad. The results verify the theoretical analysis on LD-FLA, and the model provides guidance for others on the practical design of LD-FLA.