| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk unit which enables an optical disk to be instantly, quickly, and smoothly discriminated without harming recording and reproducing characteristics of the optical disk. <P>SOLUTION: The optical disk having two data recording surfaces is provided with a memory layer using a laser beam of 650 nm wavelength where a mirror area is placed between a clamping area and a program area. Whereas, a nano area is placed in a part of the mirror area on the data recording surface using a laser beam of 405 nm wavelength. In the nano area, a rugged structure whose pitch in an intra-plane direction is 250 nm and whose depth is 170 nm is formed. A reflectance of the data recording surface with the rugged structure greatly lowers against a reflectance in the case of flat structure. Hence, the irradiation of a position corresponding to the mirror area and a position corresponding to the nano area each with the laser beam of 405 nm wavelength enables each memory layer of the mounted disk to be discriminated on the basis of the reflectance of both positions observed in the irradiation. <P>COPYRIGHT: (C)2007,JPO&INPIT |
