基于快速稀疏扫频干涉的动态间隙测量方法

A dynamic clearance measurement method based on a fast sparse frequency-swept interferometry

本文建立了基于扫频干涉的动态间隙测量模型,推导出间隙与多普勒误差、光源扫频速率之间的关系式;定义多普勒误差修正系数,对多普勒误差进行补偿。分析了扫频速度变化时的间隙瞬时频率变化特征,获得傅里叶变换频率解调法的适用条件。仿真分析了间隙以三角波形式变化情况下,稀疏扫频点数、噪声等对傅里叶变换解调的影响;进而分析了该方法在篦齿间隙测量中的适用性。最后,搭建快速稀疏扫频干涉间隙测量系统并开展动态测量实验,结果表明:扫频分别速率为20、40及60 kHz,间隙变化频率分别为100、500及1000 Hz的情况下,测量均方误差不超过0.2μm,重复性误差小于0.3μm。

In this article,a dynamic clarance measurement model based on the swept frequency interferometry is formulated.The relationship among the clarance,Doppler error and light source sweeping speed is deduced.The Doppler error correction coefficient is defined to compensate for the Doppler error.The characteristics of the instantaneous frequency change of the clarance are analyzed when the sweeping speed is changed.And the applicable conditions of the Fourier transform demodulation method are obtained.The influence of the number of sparse frequency sweeping points and noise on Fourier transform demodulation is simulated and analyzed when the clarance changes in the form of a triangular wave.Then,the applicability of the method in Clearance of labyrinth measurement is analyzed.Finally,a clearance measurement system based on a fast sparse frequency-swept Clearance of labyrinth interferometry is setup and dynamic measurement experiments are carried out.Results show that the mean square error of measurement is less than 0.2μm when the sweeping rate is 20,40,and 60 kHz,respectively.The clarance change frequency is 100,500,and 1000 Hz,respectively.And the repeatability error is less than 0.3μm.