Track access and laser beam alignment system for an optical recording

Abstract

A track access operation system for an optical recording and reproducing apparatus using a medium having a plurality of guide grooves and ID sections utilized for identifying a particular guide groove. The intensity of reflected light and transmitted light from each of a plurality of light beams projected on the recording medium is monitored for determining the location of the beam on the disk. The system is designed such that at least either the plurality of light beams or the plurality of ID sections of the guide grooves are so arranged such that more than half of the light beams or more than half of the ID sections do not overlap in a parallel direction along the guide grooves whereby the number of light beams simultaneously projected on the ID sections is limited to less than half of the total number of light beams projected on the recording medium. Accordingly, even when the collection of light beams move in a perpendicular direction to the guide grooves, the number of pulses in the pulse signal is not influenced by the ID signals but coincident with the number of the guiding grooves through which the light beams have actually passed. With use of the optical memory system having such an arrangement, an accurate measurement of light beam movement is obtained resulting in high accuracy of access operations.