| 摘要 |
PURPOSE:To stably control the optical output of a semiconductor laser and to obtain a semiconductor laser controller which can accelerate a rise at the time of igniting a semiconductor laser by varying the frequency of a clock input to an incremental/decremental counter in response to the amplitude of the absolute value of an error signal output from a comparator. CONSTITUTION:The counted result of an incremental/decremental counter 16 is converted by a D/A converter 19 into an analog signal, input to a semiconductor laser driver 20, and a current proportional to the input signal is supplied to a semiconductor laser 11. The absolute value of an error signal from a comparator 14 is obtained by an absolute value circuit 17, an oscillation frequency is varied, and an output signal is input as a clock to the counter 16. Thus, when the error signal from the comparator 14 is large, since a variable oscillator 18 is so composed as to enhance the oscillation frequency, the optical output of the laser 11 rapidly approaches an optical power to be obtained. When the error signal from the comparator 14 is sufficiently small, since the oscillator 18 is so composed as to sufficiently reduce the oscillation frequency, a stable optical output having no ripple can be obtained from the laser 11. |
