Patent ID: 6130749
Filing Date: 2000-10-10
Classification: G01B

Abstract:
A method for measuring a lubricant degradation on a thin film disk having an absorbing layer, comprising the steps of:(a) transmitting a light signal toward a selected location of the disk at a first angle, said first angle at an angle between zero degrees from vertical and ninety degrees from vertical but not at substantially Brewster's angle of the absorbing layer;(b) selectively polarizing said light signal, said polarization one of a P linear polarization, an S linear polarization, and a combination of said P linear and S linear polarizations;(c) said polarized light signal impinging upon the disk causing a specular component of the polarized light signal to be reflected off of the disk at substantially said first angle and causing a scattered component of said polarized light signal;(d) receiving said specular component from said selected location;(e) collecting said scattered component in a collector positioned substantially adjacent to said thin film disk;(f) receiving said scattered component collected in said collector;(g) identifying a plurality of locations on said thin film disk as the selected position; and(h) repeating steps (a) through (D for each of said selected positions.(i) generating a histogram representation based upon said specular and scattered components for each of said selected locations; and(j) identifying the lubricant degradation of the thin film disk based upon said histogram representation.