Patent ID: 8270285

Claim:
An optical disc manufacturing method, comprising: a mastering step of producing an optical disc master formed with concave and convex marks synchronized with an integral multiple of a channel bit length in accordance with modulated main information; a stamping step of transferring the concave and convex marks of the optical disc master to an optical disc substrate; a sputtering step of forming a reflective film on the optical disc substrate; and a sub-information recording step of irradiating continuous or intermittent laser light synchronized with the integral multiple of the channel bit length at intervals longer than a longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks to change an optical characteristic of the reflective film after the reflective film is formed on the concave and convex marks of the optical disc in the sputtering step, thereby forming a recordable mark to record sub-information necessary to reproduce the main information in a superimposition manner, wherein the recordable mark is formed on the spiral track formed in the circumferential direction of the concave and convex marks.