Patent ID: 6198533
Filing Date: 2001-03-06
Classification: G01B

Abstract:
A method for measuring one of a lubricant thickness and lubricant degradation on a thin film disk in a high temperature environment, the thin film disk having an absorbing layer, and for measuring a roughness of said thin film disk, comprising the steps of:(a) transmitting a light signal toward a selected location of the disk at a first angle using a high temperature laser diode, 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 using a temperature compensated quartz half plate, 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) determining one of the lubricant thickness and lubricant degradation based upon the specular component of said polarized light signal; and(h) determining the surface roughness of said thin film disk based upon said collected scattered component and said specular component.