| 摘要 |
PURPOSE:To prevent the chromatic aberration of a laser diode from being generated by controlling laser power by changing the duty of a high frequency superimpose pulse supplied from a high frequency supplying device. CONSTITUTION:By using a duty controller composed of a variable delay circuit 2, AND element 3, OR element 4 and switch element 5, the duty of the high frequency superimpose pulse is changed and the laser power is controlled at the time of reproducing. Accordingly, reproducing power and recording power is not obtained by the change of a current value and a current is set to a fixed value. Thus, at the time of reproducing, the power is not affected by a lower limit value for operating the laser diode and further, the chromatic aberration caused by a change in each wavelength of the laser diode does not go to be a problem. |
