| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium performing stable recording/reproduction during high speed rotation using an optical system provided with a blue laser. <P>SOLUTION: The optical information recording medium has a disk like substrate wherein distribution of birefringent amounts having a negative polarity is provided in a recording area for recording and reproducing information by irradiation with light from one side so that birefringence based on stress generated during high speed rotation is previously canceled, is rotated at a fixed linear speed and ≥6,000 rpm rotational frequency and has a push-pull signal (Pp) of ≥0.2 obtained by an optical pickup having wavelength λ of 405 nm and an numerical aperture NA of 0.65 and the ratio (P<SB>pmax</SB>/P<SB>pmin</SB>) of ≤1.4 of the maximum value (P<SB>pmax</SB>) to the minimum value (P<SB>pmin</SB>) of the push-pull signal. <P>COPYRIGHT: (C)2008,JPO&INPIT |
