| 摘要 |
PURPOSE:To enable a laser ray source which outputs laser rays of specified wavelength and output power to be offered by a method wherein a pumping light is fed, the wavelength of the pumping light is monitored, the drive current of a means which supplies the pumping light is made to change so as to obtain the pumping light of required wavelength, and an attenuation means placed in an optical path is electronically controlled in absorption characteristics. CONSTITUTION:Three photodetectors 21, 22, and 23 adjacent to one another are arranged in the optical path of diffracted light so as to enable light of required wavelength to be incident on the central photodetector 22 at an angle of prescribed diffraction order, and the drive current of a laser diode 3 is so controlled as to make the optical signal from the photodetector 22 maximal. The direction of the optical signal change can be judged by the optical signals of the photodetectors 21 and 23. The output change of the photodetector 22 attendant on the change of the drive current is so compensated by a liquid crystal attenuator 25 placed in the optical path as to make the output constant. That is, the liquid crystal is made to change in transmittance by adequately adjusting a voltage applied to the liquid crystal corresponding to the output change of a laser diode attendant on the change of the drive current to keep the transmitted light constant. |
