A Wide Range Measuring System for Thin Lubricating Film: From Nano to Micro Thickness

This paper introduces a newly developed lubricating-film-thickness measuring system, which implements the multi-beam intensity-based (MBI) scheme proposed recently by the authors. Some details about the software of the testing system and instrumentation of the MBI approach are discussed. For efficient determination of the fringe order range of measured points, a simple counting strategy was suggested. It is shown that this measuring system can provide a measurement range from nano to micrometers and a high resolution on the nanometer level. Besides being able to detect ultra-thin lubricating film thickness, the system can also measure tiny local variations in film thickness on a nano-scale in the conventional EHL regime. The capability of the system is demonstrated by the determination of film thickness in the range of 1nm to 2.542m with a standard deviation of 0.89nm. In addition, some analyses are given for further understanding the optical EHL and the testing system in this paper.