| 摘要 |
PURPOSE:To lower the coherency of an output beam and to reduce the distortion and the noise caused by the reflected light, by giving the modulation of the pulse duration to a signal to be modulated, detecting an optical signal responding to the output of the modulation to convert it into an electric signal and then demodulating the output to feed it negatively back to a modulating part. CONSTITUTION:A modulated wave signal 18 given from a modulated wave oscillator 16 is amplified by an amplifier 9 and fed to a pulse amplitude modulating circuit 8 via an input terminal 7. The signal 18 receives the pulse modulation with a pulse modulating signal 17 given from a modulated signal oscillator 15 having a frequency twice or more as much as that of the signal 18. The signal 18 is then converted into an optical signal by a laser diode 1. A part of the optical signal is detected by a photodiode 2 and converted into an electric signal 19 with the modulated wave component 20 demodulated by a demodulator 13. The signal 19 is fed back to an input terminal 12 of the amplifier 9 via a feedback circuit 14. |
