润滑膜厚测量的双色光干涉强度调制方法

A Dichromatic Interference Intensity Modulation Approach to Lubricating Film Thickness Measurement

提出一种红绿双色光干涉强度调制技术(DIIM)对球盘接触润滑油膜厚度进行测量.利用接触区外部干涉图像中红、绿分量强度值之差得到调制信号,并由此得到对应特征点的条纹干涉级次,进而由干涉强度得到接触区内任一点膜厚.运用多光束干涉理论对所提出的测量技术进行了原理分析,讨论了所用双色光的光波长、半峰全宽、测量介质对测量结果的影响.最后,应用该技术分别对球盘接触的静态间隙和动态油膜厚度进行测量,结果与经典理论有很好的一致性,证明了该技术的可行性.对试验所用的双色激光光源(红光653 nm、绿光532 nm),光学量程可达4μm.由于光强衰减小且能避免干涉级次计数,该方法可高效测量润滑油膜厚度.

A dichromatic( red- green) interference intensity modulation( DIIM) approach is proposed for ball- on- disk lubricating film measurement. In this approach,a modulated signal,obtained by intensity subtraction between the red and the green components in the interference outside the contact area,was used to infer the fringe order of characteristic locations.Thereafter the film thickness of other locations can be determined by the intensity. This approach was analyzed with multi-beam interference,and the influences of wavelengths,FWHM of the light source and the lubricants' refractive indices were discussed. To validate the feasibility of this approach,the static contact gap and dynamic film thickness between a steel ball and a glass disc were measured,and the results were well correlated with the classical theories. With the red laser of 653 nm in wavelength and the green laser of 532 nm in wavelength,the measurement range can be as high as 4 μm. Since there were no obvious intensity attenuates and no artificial fringe order counting,this approach can be used to evaluate film thickness efficiently.