| 摘要 |
PURPOSE:To optimize a recording output light by detecting a time aging deterioration of a semiconductor laser by utilizing an intrinsic pattern of a recording data, controlling a driving current of the laser based on said detection, and keeping an optical output at the time of recording roughly constant. CONSTITUTION:By an intrinsic pattern of a recording signal, an optical output of a laser diode RD 1 is brought to a photoelectric conversion by a photodiode PD 2 and a current-voltage converting circuit 3. Its output is compared with a reference voltage by an optical output detecting circuit 7, and when it is lower than the highest output at the time of recording, a signal being proportional to its difference is outputted. While a recording signal pattern is being outputted, a changeover switch 8 becomes ON, and a driving current controlling circuit 9 controls a driving current of a driving current circuit 5 by an output signal of the circuit 7. When recording is ended, the switch 8 becomes OFF, an output value of the circuit 7 is saved in the circuit 9, and a recording signal drives the RD 1 by a driving current. In such a way, a recording output light is always maintained in an optimum state. |
