A magneto optical head assembly combining a single high extinction polarizing beam splitter utilized to separate and analyze a light beam, a pair of half-wave plates, each having a fast axis with respect to the polarization direction of light transmitted through the head assembly, with the angle of the fast axis of one of the half-wave plates preferably being equal but opposite that of the angle of the fast axis of the remaining half-wave plate. The light beam is transmitted through the head assembly polarizing beam splitter to be polarized with one half of the transmitted polarized light passing through one of the half-wave plates and the remaining half of the transmitted polarized light passing through the other half-wave plate. The portion of the transmitted polarized light which passes through each half-wave plate is rotated about the fast axis of each plate and focused upon a point on a magnetic recording medium. The light is reflected off the magnetic recording medium, with its attendant Kerr rotation, back through the other half-wave plate into the polarizing beam splitting portion of the head assembly. The beam splitter directs a portion of the reflected light beam to a pair of photo detectors. The polarizing output signals of these detectors are coupled into a differential amplifier where the common signal components cancel, leaving only the Kerr rotation signals component which is indicative of the magnetization state of that point on the magnetic recording medium where the light is focused.