| 摘要 |
PURPOSE:To obtain good quality laser light without external noises by a method wherein a part of the laser light from a gas laser tube is detected via an optical fiber cable. CONSTITUTION:The laser light 13 a part of the laser light 12 becomes incident to the optical fiber cable 15, and then the laser light 13' passing through the cable 15 is detected by a photodetector 6, resulting in the appearance of photo output voltage at both ends of a resistor 5. The difference voltage between said light output voltage and a reference power source 4 is amplified by a comparing amplifier 3 and then supplied to the base of a transistor 2, thus controlled so that the difference voltage becomes zero. Since detection is performed via the optical fiber cable in this manner, external noises, particularly power source noises for commercial use do not mix into the light output voltage, and the external noises do not mix into the laser light 13'. Therefore, the external noises do not appear in the output of the amplifier 3, and in the laser light 12. Thus, good quality laser light without external noises can be obtained. |
