| 摘要 |
PURPOSE:To always hold the photo output of a laser beam constantly by a method wherein part of the laser beam after being made to pass through the polariscope is branched, the part is guided into the photodetector and a current feedback is performed on the laser so that the output of the photodetector becomes constant. CONSTITUTION:The emitted light of a semiconductor laser 21 is made in parallel by a collimator lens 22 and is made to pass through a polariscope 23. After that, part of the emitted light is branched by a non-polarization beam splitter 24, the part is received by a P-I-N photo diode 25 and a current feedback is applied on the laser 21 so that the photocurrent of the diode 25 becomes constant. According to this constitution, the emitted light after being polarized becomes always constant even when a temperature change occurs and a very useful optical information device can be obtained. |
