| 摘要 |
PURPOSE:To enable a laser beam output to be controlled stably and in a high frequency hand. CONSTITUTION:At the time of reproducing operation, a high frequency component and a low frequency component are separated from an output current of a photodiode PD by a CR filter 62, and only the low frequency component is amplified and afterward added to the current, and this added current is converted into a voltage by an amplifier A2, and then a light emitting quantity of a laser beam by a laser diode 9 is controlled in accordance with this converted voltage. At the time of pulse light emitting during the recording time, the monitor loop is opened, and a voltage corresponding to a recording pulse is superimposed upon a reproducing output voltage charged in a capacitor C1 in the CR filter 62, and then the light emitting quantity of the laser beam by the laser diode 9 is controlled according to this voltage. |
