Optical signal processing apparatus for detecting the direction of movement of an optical reading device relative to an optical disk

According to this invention, an optical signal processing apparatus for an optical disk has an actuator for moving an optical head in an radial direction of the optical disk, a plurality of first photodiodes for receiving a light beam reflected by the optical disk, an addition circuit for generating a first sum signal representing a sum of signals from the first photodiodes, a polarizing beam splitter for splitting the light beam reflected by the optical disk in accordance with directions of polarization, a plurality of second photodiodes for receiving light passing through the polarizing beam splitter, a subtraction circuit for generating a difference signal representing a difference between signals from the second photodiodes, and a circuit for determining a moving direction of the optical head, using the sum signal and the difference signal during a seek operation. Since the sum signal includes no data signal component, the moving direction of a light spot during a seek operation can be accurately determined, thereby performing a reliable seek operation.