| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk which has enhanced heat resistance while transparency is maintained, attains satisfactory recording and reproduction even when internal stress exists and uses a polylactic acid. <P>SOLUTION: In the optical disk 1 wherein a reflection layer 3 or a recording layer and a first protective layer 4 are sequentially layered on a rugged pit of a light transmissive substrate 2 mainly composed of the polylactic acid, a second protective layer 5 is formed on the side opposite to the layered direction of the light transmissive substrate 2 and reproduction of information of the rugged pit or recording and reproduction of the recording layer are performed by irradiation with a laser beam from the second protective layer 5 side, the second protective layer 5 is made of a transparent inorganic material. <P>COPYRIGHT: (C)2008,JPO&INPIT |
