Mechanically amplified MEMS optical accelerometer with FPI readout

Abstract

We have developed a silicon MEMS optical accelerometer in which the motion of the proof mass is mechanically amplified using a V-beam mechanism prior to transduction. The output motion of the V-beam is detected using a FabryPérot interferometer (FPI) which is interrogated in reflection mode via a single-mode optical fibre. Mechanical amplification allows the sensitivity of the accelerometer to be increased without compromising the resonant frequency or measurement bandwidth. We have also devised an all-optical method for calibrating the return signal from the FPI, based on photothermal actuation of the V-beam structure using fibre-delivered light of a different wavelength. A finite-element model has been used to predict the relationship between the incident optical power and the cavity length at steady state, as well as the step response which determines the minimum time for calibration. Prototype devices have been fabricated with resonant frequencies above 10 kHz and approximately linear response for accelerations in the range 0.01 to 15 g.

An Optical Measuring Transducer for a Micro-Opto-Electro-Mechanical Micro-g Accelerometer Based on the Optical Tunneling Effect

“…In the wave-optics-based accelerometers, the acceleration alters the parameters of the light flux (phase, frequency, intensity, etc.). MOEM-accelerometers based on wave optics are tunnel, grating or interferometric resonators [22][23][24], Fabry-Perot resonators [25][26][27][28], photon crystals [29][30][31] and others. At present, MOEM-accelerometers based on the fiber Bragg grating (FBG) with direct integration into optical fiber are widely used [32][33][34][35].…”

A MEMS Fiber-Optic Fabry-Perot Vibration Sensor for High-Temperature Applications

“…Different fabrication methods have been used to manufacture the sensing elements of fiber-optic sensors, including micro-machining, laser ablation, chemical etching, MEMS technology, etc. [12][13][14][15][16]. In the previous work, we proposed the two fiber-optic Fabry-Perot (F-P) accelerometers, of which the steel circular diaphragm and brass cantilever micromachined as the sensing elements, respectively [17][18].…”

“…Edward et. al [16] reported a silicon MEMS F-P optical accelerometer, in which the displacement of the proof mass is mechanically amplified by a V-beam structure prior to transduction. Compared with machining, chemical etching processing and laser processing, the sensor based on MEMS processing technology has the advantages of mass production, low cost and good consistency.…”