High-Precision Head Positioning Using Multiple Offset Beams

This paper describes a new tracking technique with a multiple beam mechanism that will lead to low profile optical disk storage units with faster access speeds. In this technique, data tracking involves selection among multiple beams with minute offsets. It can accommodate four-beam laser diodes while assuring twice the tracking accuracy and ten times the tracking bandwidth of conventional approaches. Its servo performance depends on the total distance between the two outermost beams in the beam series on the medium.