OPTICAL DISC MEMORY HEAD

PURPOSE:To obtain a head capable of forming various kinds of magnetic fields with simple structure by providing magnetic field applying magnetic poles made nearly orthogonal to each other, using the magnetic poles so as to form a rotating magnetic field, a couple of polarized plane analyzers whose analyzed planes are made nearly orthogonal and a couple of photodiodes detecting the detected light. CONSTITUTION:A synthesized magnetic field comprising magnetic fields 305, 306 formed by magnetic field applying magnetic poles 303, 304 made nearly orthogonal to each other at write causes magnetic polarization onto a magnetic film 308 for writing. In changing H1n, H2n, the synthesized field is directed in an optional direction thetan to form a magnetic field Hn having a prescribed strength. The analyzer 404 passes through only a light having the polarized plane in the direction of arrow 405 and the analyzer 403 passes through only a light having a polarized plane perpendicularly to this paper and the analyzed planes are made orthogonal. In reading the rotated quantity of the polarized plane, a code value (n) in a spot is read. Thus, the returned light is divided into two by a beam splitter 110, they pass through the analyzers 111a, 111b arranged to have orthogonal analyzed planes are received by photodiodes 106a, 106b.