An Optical Integrated Vibration Instrument

Vibration acceleration sensor with high performance and high stability has been a hot research topic in the field of engineering technology,which also plays an important part in the machine health monitoring system.Traditional piezoelectric vibration sensor has excellent performance,rich product series,but it lose advantages in terms of heavy weight.MEMS accelerator market develops rapidly in recent years,and it is gaining more and more attention under the background of IoT,but most MEMS accelerator works on the principle of electrical measurement,which cause bad performance in a more complex electromagnetic environment.The ideal choice,MOEMS vibration sensor,has not been able to enter the market widely due to its difficulties in R&D,lacking of precision or its high price.From piezoelectric,MEMS to MOEMS,the measuring principle,structure design and manufacturing process of vibration sensor are becoming more and more abundant,especially the design of vibration sensing unit optimizes a lot.In reference to the vibration sensing unit of MEMS and MOEMS,this article mainly study on high stability,price economic vibration acceleration sensor based on the optical measurement.According to the mechanical model of vibration accelerometer,two key factors that determine the resolution of accelerator are analyzed: frequency response characteristics of vibration sensing unit and absolute displacement-measuring resolution.In terms of the vibration sensing unit's frequency response characteristic,a vibration information enlarging resonance coupling structure is designed to extend the bandwidth of acceleration measurement.In terms of displacement-measuring resolution,a simple and stable grating displacement measurement system is proposed.In the simulation of resonant coupling structure,the effects that natural frequency,coupling spring elasticity coefficient have on double cantilever beam coupling frequency response are analyzed.On the basis of two-beam coupling theory,this article uses the finite element analysis software ANSYS to design and optimize a set of beam resonance coupling array(with ideal spring)to accomplish a measuring bandwidth for 5 Hz(109Hz-114 Hz).Finally,a set of in-plane coupled array beams with a measuring bandwidth of 19.8 Hz(268Hz-287.8Hz)were designed and optimized to satisfy planar processing technology,and the expansion of vibration measurement bandwidth was realized.In the displacement measurement system,by configuring appropriate grating constant and laser convergence system,the experiment shows that the displacement measurement system can achieve precision measurement with a resolution of at least 1.5?m.Higher resolution can be achieved by division of photoelectric signals.Combining the displacement measurement system and the resonant coupling structure,theoretically the design of vibration acceleration measurement instrument proposed in this article can realize 1 mg(109Hz-114Hz)and 11mg(268Hz-287.8 Hz)acceleration measurement resolution.