JP2926899B

PURPOSE:To allow tracking control by using an optical system of the same space cut-off frequency as heretofore while having the recording tracks of the density equivalently twice larger than the conventional density by forming the tracks by shifting the beginning end of the prepattern which follows the terminal of the preceding prepattern by 1/2 the track pitch. CONSTITUTION:Spiral guide grooves G are parted at every one round on the same radius of the disk, by which plural pieces of the guide grooves Gi, Gj are formed. These grooves are formed by shifting the beginning end Gjs of the guide groove by 1/2 the track pitch p from the terminal Gif of the preceding guide groove. The groove parts and 'partition' parts or the 'partition' parts and the groove parts are, therefore, respectively continued in the track direction in the parted regions. The recording tracks of the density equivalently twice larger than heretofore are formed in this way. The tracking control by using the optical system of the same space cut-off frequency as heretofore is thus possible.