| 摘要 |
PURPOSE:To enable to select the frequency of oscillation much larger than a lock-in frequency by the reduction of the scattered lights from all reflection mirrors to zero in an ideal manner by a method wherein a reflection mirror is subjected to angular oscillation. CONSTITUTION:Passages 12-14 almost of a triangle made of a crystallized glass block 11 are formed in the title device, and anodes 18 and 19 are provided in the middle of the passages 12 and 14, and a cathode in that of the passage 13. The reflection mirrors made of concave mirrors 15 and 16 and a plane mirror 17 are provided by corresponding to the light path 22 of each laser beam, and then two laser beams are put into rotational advancement in reverse to each other. This device is provided with a piezoelectric oscillating device as an oscillating means which varies the angle of this plane mirror 17 around an incidence end 23 by oscillation. A piezoelectric element 27 is interposed between the outer peripheral surface of this movable part and the inner peripheral surface of a fixed part, and then driven by AC signals from a control part 28, thus supplying the light path passing through the reflection point of the mirror 17 with pivots around a vertical axis. The reflected lights from all the reflection mirrors are reduced to zero, and the frequency of oscillation is selected larger than the lock-in frequency. |
