MEMS Fabry–Pérot optical accelerometer employing mechanical amplification via a V-beam structure

Sensors and Actuators A: Physical, online 23 August 2013.

Edward Davies, David S. George, Malcolm C. Gower, Andrew S. Holmes. 

Imperial College London, EEE Department, Exhibition Road, London SW7 2AZ, UK and

AWE plc, Aldermaston, Reading, Berks RG7 4PR, UK.

 

Abstract

We report a silicon MEMS optical accelerometer based on the Fabry–Pérot interferometer (FPI) principle in which the displacement of the proof mass is mechanically amplified by a V-beam structure prior to transduction. Mechanical amplification allows the sensitivity obtained with a given readout system to be increased without compromising the sensor bandwidth. The FPI cavity in our device is formed between a mirror situated on the V-beam and reflections from the end surface of a cleaved optical fibre. Simple analytical expressions have been derived for the amplification factor of the V-beam structure, in terms of its geometrical parameters, and for its mechanical stiffness which affects the resonant frequency. These were used to design a series of five accelerometers with different mechanical amplification factors which were fabricated and tested. A device having a V-beam angle of 1.9° was capable of detecting accelerations over a dynamic range of 103 between 0.01 g rms and 10 g rms, while a 1.33°angled device achieved the largest amplification of 18.6 ± 6.4.

 

Go To Journal

 

Additional Information

Optical accelerometers are highly sensitive, require no electrical signals and are immune to electromagnetic radiation. This makes them attractive for structural health monitoring for harsh environment applications including nuclear power plants, the oil and gas industry and defence. In all open loop accelerometers there is an inherent trade-off between sensitivity and bandwidth while optical fibre based accelerometers are constrained by the physical dimensions of the fibre itself. The accelerometers presented are fabricated in silicon using MEMS processing techniques giving great control over the size of the proof mass and the value of the spring constants. Further to this, a V-beam is employed to amplify the displacement of the proof mass thereby allowing for a high resonant frequency without sacrificing sensitivity.

This work was sponsored by AWE plc.

Figure Legend

A photograph showing the fabricated accelerometer with the optical fibre in place and secured with glue.Situated next to a British pound coin for scale.

 

MEMS Fabry-Pérot optical

Check Also

Advancing Fusion Energy: High-Field REBCO Superconducting Magnets in the SPARC TFMC Program - Advances in Engineering

Advancing Fusion Energy: High-Field REBCO Superconducting Magnets in the SPARC TFMC Program