A magneto-optical disc (1) responds to light generated by a laser (2) that generates an emission which passes through a collimate (3), beam splitter (4) and focussing lens (5). Signals reflected from the disc are directed by the beam splitter to an analyser (8) which passes only light with a specific polarising angle. The signals are received by a detector. All the units form the optical head module (12). The recording of information on the disc requires that the disc temp. is raised above the Curie point. A magnetic drive stage (15) provides a modulating effect. The laser (2) is also controlled by a drive circuit (16) which varies the intensity of the optical beam.