| 摘要 |
PURPOSE:To optionally change the rate of reflected light to transmitted light by forming a light transmitting part and a light shielding part on a rotary member so that transmissivity when the radiating position of a laser beam to the rotary member is changed in a radiating direction is changed and forming the light shielding part as a reflecting mirror face. CONSTITUTION:The light transmitting part 19 for optionally transmitting laser beams and the light shielding part 21 for optionally shielding light are formed on the rotary member 17 and one side face of the light shielding part 21 is formed like a reflecting mirror face so as to reflect laser beams efficiently. When the light transmitting part 19 of the rotary member 17 is positioned in the optical path of a laser beam LB radiated from a laser oscillator at the time of rotating the rotary member 17 at a fixed speed, the laser beam is transmitted through the rotary member 17. When the light shielding part 21 of the member 17 is positioned in the optical path, the laser beam is reflected. Thereby, the laser beam can be split into transmitted light and reflected light. The rate of the transmitted light to the reflected light can be optionally changed by changing the position of the rotary member in the radius direction crossing the optical path.
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