| 摘要 |
PURPOSE:To ensure the tracking stability in a reproduction mode by setting the depth of a guide groove at <=500Angstrom and also at >=0.02lambda/n (lambda: light wavelength, n: refractive index of substrate) respectively. CONSTITUTION:The depth of the guide groove of a disk substrate is set at <=500Angstrom and also at >=0.02lambda/n respectively. The tracking performance is deteriorated if the depth of the guide groove is set at <=0.02lambda/n and the tracking control is difficult. While the effective sensitivity is deteriorated if the depth of the groove is set at <=500Angstrom and the recording power must be increased. Then it is not desirable to increase the laser pulse width in a write mode to reduce the recording power because the tracking stability is deteriorated. |
