Patent ID: 6717671
Filing Date: 2004-04-06
Classification: G01B

Abstract:
A method for measuring a first phase difference between first and second reflected polarized light signal components, the method comprising the steps of:transmitting a first incident light signal toward a first object, wherein said first object is a magnetic disk; separating from a reflected light signal that has reflected off said first object a first mixed reflected polarized light signal component having a first phase and a second mixed reflected polarized light signal component having a second phase that is different from said first phase, wherein said first mixed reflected polarized light signal component comprises both P-polarized and S-polarized light relative to a plane of incidence of said reflected light signal, and wherein said second mixed reflected polarized light signal component comprises both P-polarized and S-polarized light relative to the plane of incidence of said reflected light signal; detecting a first intensity of said first mixed reflected polarized light signal component; detecting a second intensity of said second mixed reflected polarized light signal component; and determining a difference in phase between said first and second mixed reflected polarized light signal components based upon said first and second intensities.