Development of an all-optical temperature insensitive nonpendulum-type tilt sensor employing fiber Bragg gratings

A design strategy for the development of an all-optical, temperature insensitive, nonpendulum-type tilt sensor employing fiber Bragg gratings (FBGs) is proposed and experimentally demonstrated. Being nonpendulum-type, there is no possibility of any inherent friction and the limiting effects at mechanical joints. The sensor is observed to be capable of measuring magnitude, as well as the direction of inclination from horizontal strategically more effectively and without any inherent instability. This is reflected in a relatively better resolution (better than 0.004°), a better accuracy (~±0.05°), and a lesser maximum discrepancy (~±0.001  nm) during the forward as well as the reverse tilt. Sensitivity of the proposed sensor, theoretically proportional to the half of the mass employed in the sensor design, is observed to be 0.012  nm/° with a comparatively smaller mass. Importantly, sensor response is characterized by a very high degree of reversibility and repeatability over the designed/observed dynamic range.