On-line tribology measurements on lubricated rigid disks

A high-speed ellipsometer has been devised for online wear measurements of recording media. The instrument can either determine spatially resolved film-thickness profiles across a wear track or make high-speed measurements of the angular dependence of wear damage as the test specimen rotates. In its present configuration, data-acquisition rates of 300 Hz are possible. Experiments on thin film demonstrate the ability of the technique to monitor thin-film profiles and to reveal the progression of wear from the ablation of the lubricant layer to the removal of the magnetic film