| 摘要 |
PURPOSE:To enable high speed, high precision, and high resolution by controlling semiconductor lasers by the currents of the sum or difference between the control currents of a light/electric negative return loop, the output currents of switching, and the currents generated by conversion. CONSTITUTION:A light receiving element 4, a capacitor C, a resistor R, an impedance converter 11, a voltage/current converter 12, an adder 13, a subtracter 15, and a current amplifier 16 constitute a first light/electric negative return loop which controls the currents in the forward direction of semiconductor lasers 3 so that the photovoltaic currents Is of the light receiving element, which are proportional to the light output of the semiconductor lasers 3, and the first luminous level command signal currents IL from a voltage/current converter 14 may be equal, and a comparative amplifier 10 and a voltage/current converter 14 constitute a second light/electric negative return loop which controls first luminous level command signal currents IL so that the voltages, which are proportional to the photovoltaic currents Is of the light receiving element 4, and the second luminous level command signals from outside may be equal. Also the semiconductor laser 3 are controlled by the currents of the sum of the output currents of a switching circuit 9, the output currents of a voltage converter 2, and the control currents outputted from a comparative amplifier 1. |
