Optical disk with recesses inside an inner circumference of an information recording area and method of making same

摘要

An optical disc 1 has formed in an area inside the inner circumference of an information recording area 2 formed thereon concentric or spiral continuous or discontinuous recesses 4a at a lager pitch than the track pitch in the information recording area 2. The optical disc is manufactured by installing a hub 5 substantially in the center of an optical disc substrate with reference to the recesses 4a by positioning the hub 5 with respect to the optical disc substrate. A stamper for manufacturing the optical disc substrates is produced by exposing a photoresist layer 11 to a laser beam by turning on and off the laser beam while rotating a glass substrate 10 having the photoresist layer 11 applied thereon and scanning the laser beam radially of the glass substrate 10.