Online Measurement of Lubricating Film Thickness in Slider-on-Disc Contact Based on Dichromatic Optical Interferometry

The present study mainly focuses on a new approach to achieve online measurement of lubricating film thickness in a slider-on-disc contact. The inclination of the slider is obtained by Fourier transform and frequency estimation of the interferogram of the sliding contact. An algorithm that is based on optical flow calculation and dynamic time warping technique is presented for tracking a characteristic point with constant film thickness on the 1-D modulated intensity curve. Online film thickness measurement can thus be achieved. This approach has been validated with known gap thickness of a stationary wedge. In addition, transient film thickness under unsteady speeds was measured with the present approach and some lubrication behaviours have been revealed.