High sensitive fiber optic accelerometer with laser readout

Fiber acceleration sensors based on one end fixed fiber sections as an elastic element with own seismic mass are developed and researched. It is shown, that by reading traversal deformations of oscillating fiber sections we are able to increase accelerometers sensitvity by orders in comparison to detection of a longitudinal oscillating fibers configuration changes, as it was taken in a number of works. For precision and non-inertial acceleration detection, it is suggested to apply single frequency laser coupled to Fabry-Perot interferometer. The measuring laser system based on the single frequency semiconductor laser with a narrow linewidth (λ=1.5 μm) and single mode optical fibres was created to demonstrate basic physical properties accelerometers. This system allows to detect one end fixed fiber sections small linear traversal bend deformations, caused by inertial force. Small dielectric 100% reflecting mirror with neglecting mass was fixed on the other fiber section end. The input/output fiber end was used as the second mirror. It could be placed in few centimeters from the first one. It is experimentally approved, that 20 mm length fiber section first resonant frequency is 300 Hz. Sensor is accelerometer at low frequecnies with sensitivity range (10-6 - 10-2) m/s2, and at higher frequencies (≥2 kHz) the sensor is vibrometer, which output is in proportion to sensor case displacement. Gain-frequency characteristic at 10 Hz - 10 kHz is measured. Multiplexed and 3-D sensors are mentioned as the next goal.