Abstract: Apparatus and method for determining an orientation of magnetic domains currently being irradiated by a laser having two orthogonal linearly polarized modes of operation is described. The orientation of the currently irradiated magnetic domains determines which linear polarization mode is currently active and can be used as a readout technique for signals encoded in a magneto-optic medium. This polarization switching technique for the reading stored information is dependent on adjusting the parameters of the extended laser cavity so that excitation of each polarization mode is substantially equally probable. When the parameters of the extended laser cavity are substantially equally probable, then the difference in the attenuation of circularly polarized radiation resulting from interaction with oppositely oriented magnetic domains in a magneto-optic material determine the current polarization mode.

Abstract: A read/write head for an optical storage system is implemented using at least one liquid crystal cell, the liquid crystal cell being of the type in which the retardance of a radiation beam therethrough is determined by an externally applied voltage. In an optical storage system of the type having regions of differing absorption to determine logic states the liquid crystal cell can activated by a voltage which provides the liquid crystal cell with the characteristics of a quarter wave plate. In this configuration, the liquid crystal cell is positioned in the collimated beam between the linearizing beam splitter and the storage medium. In the optical storage system in which logic states are identified with the orientation of magnetic regions, the liquid crystal cell is positioned between the linearizing beam splitter and the beam splitter used to separate the radiation components.

Abstract: In a read/write head for a magneto-optical storage system, a optical wave plate is positioned between the partial polarization beam splitter to which the radiation from the source is applied and the analyzing beam splitter which directs the two components of the radiation beam to the differential detection system. Using the techniques herein described, equations are developed which identify the optimal parameters for the optical wave plate. The equations are derived for the retardation of the optical wave plate and for the angle of the slow axis of the optical wave plate relative to the read/write head optical coordinates. These two equations are given in terms of the phase between the s and the p polarization components. The equations are applied to the specific example wherein TbFeCo is the magneto-optical material.