| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the need for high-accuracy control of an optical pickup and to make it possible to respectively simultaneously read out the data of the two recording surfaces of two-layered structures. SOLUTION: The CD-ROM 1 having the two-layered structures is formed by superposing the first CD-ROM 11 and the second CD-ROM 12 above and below. Pit strings are formed on the first CD-ROM 11 on the upper side in the same manner as for ordinary CD-ROMs. A polarized light reflection film 11a having the characteristic to reflect an S polarized light component and to allow the transmission of a P polarized light component is deposited on the surface of these pit strings. The second CD-ROM 12 of the lower side is formed in the same manner as for the ordinary CD-ROMs. An aluminum reflection film 12a which reflects the laser beam transmitted through a disk substrate is deposited on the surface of the pit strings. The first and second CD-ROMs 11, 12 are superposed in such a manner that the positions of the pit strings thereof are aligned to each other in a vertical direction. |
