小波分析在激光自混合干涉位移传感器中的应用

为减小激光自混合干涉位移传感器测量误差,提 出了基于小波分析的自混合干涉信号 处理方法。在进行全相位快速傅里叶变 换(FFT)解调相位之前,利用离散小波分解、重构去除自混合干涉归一化信号的奇异点 ,有效降低调制电流斜率突变引入的高次 谐波干扰,同时去除高频随机噪声干扰。简述了自混合干涉位移测量原理,介 绍了基于小波分析的自混合干涉信号处理算法原理并进行了算法仿真,采用数值仿 真分析了系统反馈水平及调制参数对测量误差的影响,利用压 电陶瓷(PZT)对自混合干涉位移测量系统进行标定。结果表明,位移测量误差减小到2.45nm。应用小波分析处理干涉信号可减小激光自混合干涉位移传感器的 测量误差。

Application of wavelet analysis in laser self-mixing interferometry for displa cement measurement

In order to reduce the measurement error of the displacement sensor ba sed on self-mixing interference,a signal processing method based on wavelet analysis is proposed.Before the all-phase spectrum ana lysis,wavelet analysis is applied to remove the singular points of normalized signals.This method can reduce the impact of higher harmon ic produced by the slope mutation of modulation current and diminish the disturbing of high-frequency noise very effectively.F irst,the principle of displacement measurement based on self-mixing interference is described briefly.Second,the signal processing algorithm is i nvestigated with arithmetic simulation.Third,the influence of feedback level a nd modulation parameter on the error of displacement is analyzed by numerical si mulation.At last,experiment system is established and the calibration result of piezoelectric ceramics is presented.Experimental results indicate that the displacement error can be decreased to 2.45nm,so the wavelet analysis can r educe the displacement error of self-mixing interferometer.