| 摘要 |
PURPOSE:To prevent the deterioration, etc., of the SN ratio of a wobble signal when the magnification of a recording speed is varied. CONSTITUTION:A setting means 28 for the magnification of a recording speed sets the magnification of a recording speed by means of the manipulation of an operator, etc. An irradiating time control means 26 modulates an input FEM signal by means of an (n-1) strategy, etc., and controls the irradiation time of a recording laser beam 11. A laser power control means 25 changes a pit power in a pit period according to the magnification of a recording speed. Namely, since the thermal input per unit length decreases as the magnification of the recording speed grows high and the pit is hardly formed, the pit power is made to raise so as to form a proper pit. Simultaneously the bottom power is raised so that the difference from the pit power does not increase too large and the prolongation of the fall time of the returned waveform is prevented. |
