Mueller Matrix Tools in Magneto Optic Data Storage Systems

The operation of a Photo Elastic Modulator (PEM) type ellipsometer is described in Mueller matrix terms. The phase shift (δ) between orthogonal polarization components and the relative amplitude ratio (tan) is contained in the Mueller matrix elements and can be obtained via combinations of measured matrix elements using no mechanical motion. A phase shift measurement accuracy of ±0.2° has been obtained without calibration. The short term repeatibility of both δ and is ± 0.01°. A computer controlled implementation is described along with simple algorithms to extract the ellipsometric constants. The Mueller matrix of a magneto optic film system has been used along with one for a "leaky" beamsplitter to form the optical readout system matrix for an ideal system. One of the Stokes parameters is porportional to the differential detection signal often used in MO data detection schemes.