高灵敏度低频光学加速度计的设计

Design of high⁃sensitivity low⁃frequency optical accelerometer

在结构健康监测、地震监测和航空航天等领域,需要准确测量频率低于10 Hz和振幅小于1 mm的低频微振动,对应的加速度在mg~μg量级。现有商用加速度计的灵敏度多低于0.5 V/g,无法满足要求,故开展了高灵敏度低频光学加速度计的研究。基于加速度计的测量原理,通过理论建模确定了低频加速度计设计相关的技术要求,采用簧片和柔性铰链作为弹性元件,搭配使用单质量块和多质量块,构建了一维、二维和三维弹性机构;基于像散、激光三角法和激光自准直等高精度光学传感原理,设计了高灵敏度的光学传感系统;最终完成了一维、二维和三维低频光学加速度计的设计,并通过实验验证了所设计加速度计的性能,其灵敏度均优于9 V/g,分辨力均优于1 mg,可以用于低频微振动的测量。

In the fields of structural health monitoring,seismic monitoring,and aerospace,low⁃frequency micro⁃vibrations with frequencies below 10 Hz and amplitude less than 1 mm need to be measured accurately.The acceleration values of low⁃frequency micro⁃vibrations are on the order of mg~μg,while the sensitivity of existing commercial accelerometers is mostly below 0.5 V/g,which can no longer meet the requirements.In this paper,high⁃sensitivity low⁃frequency optical accelerometers is carried out.Based on the sensing principle of accelerometers,the technical requirements related to the design of low⁃frequency accelerometers are determined through theoretical modeling,and one⁃dimensional(1D),two⁃dimensional(2D),and three⁃dimensional(3D)elastic mechanisms are constructed by using leaf springs and flexible hinges as elastic elements with single and multiple seismic masses;based on high⁃precision optical sensing principles such as the principle of image dispersion,laser triangulation,and laser auto⁃collimation,a high⁃sensitivity optical sensing system is designed.1D,2D and 3D low⁃frequency optical accelerometers have been designed and their performance has been verified by experiments,with sensitivity better than 9 V/g and resolution better than 1 mg,which can be used for lowfrequency micro⁃vibration measurements.