Optical media tracking method and apparatus for optical storage system

摘要

An optical data read/write apparatus is disclosed for use in reading a rotating optical disc having at least one concentric reference track and circular data tracks thereon. The apparatus includes an optical head which includes separate tracking and data beams directed onto the disc. The optical head is supported on a carriage which is movable by a linear actuator for movement radially relative to the disc. A substantially continuously operable closed loop servosystem which includes the linear actuator causes the tracking beam to follow the reference track. The data beam is movable relative to the tracking beam and is moved so as to follow a selected data track. A plurality of concentric reference tracks may be included on the disc in which case the linear actuator is supported on a second carriage movable in the same direction as the carriage that supports the optical head. A stepper motor controls the position of the second carriage for coarse positioning of the tracking beam relative to a selected reference track. Reference tracks may be recorded at a frequency outside the frequency range used for recording data tracks to allow for easy discrimination between reference and data tracks.