| 摘要 |
PURPOSE: To prolong the service life of a laser diode by comparing an actual value of the optical output of the laser diode with a target value, reducing the target value in the operation system of control data evaluation or by error rate signal input of a data code. CONSTITUTION: The output signals of a preamplifier 2 are supplied to a control stage 7 through a converter 4 to control the optical output of a laser diode. A comparator 8 of the stage 7 compares the output value of an AD converter 6 with the target value of a memory 9 and connects the output value to the output side through a switch 15. The switch 15 is controlled by an operation mode switch 16. The switch 16 has various operating positions and outputs a low laser output when the selected mode is a reading only of control data and outputs a high laser output during the reproducing of effective signals. Thus, the service life of the laser diode is prolonged. |
