| 摘要 |
PROBLEM TO BE SOLVED: To realize laser power control by a small-scale and inexpensive system structure. SOLUTION: A photodetector 13 detects the intensity of an incident laser beam from a laser light source 11 through a polarizer 12, and supplies it to a noise eater circuit 14. The noise eater circuit 14 computes the displacement of the laser beam intensity from the photodetector 13, determines in a feedforwarding manner the correction quantity of the polarizer 12 according to the displacement, and supplies a control signal for that correction quantity to a motor driving part 15 for rotating the polarizer. This driving part 15 is driven in accordance with the control signal from the noise eater circuit 14, and rotates the polarizer 12. A managing part 17 for the rotary angle and position of the polarizer controls the motor driving part 15 for rotating the polarizer, and limits its rotary angle. |
