| 摘要 |
PURPOSE:To provide a device to correct angular displacement of a beam of light caused by environmental change unpredictable such as vibration, voltage, etc. CONSTITUTION:Dislocation information of a received beam spot on the photo- receiving surface of a photo-receiving element (for example, quadri partitite sensor) 8 provided for position sensing is sent to a mirror drive controlling part 12 as an optical axis shift correct signal via a signal processing part 11, to actuate a motor in the drive part of a mirror angle varying mechanism part 10, which rotates a total reflection mirror round two axes perpendicularly intersecting on the mirror face, and thereby the cycle of moving the beam spot is repeated so that the center of the beam spot is positioned in the neighborhood of the center of the photo-receiving surface of the photo-receiving element for position sensing. This is combined with rotation round the axis identical to the optical axis 13 on the beam splitter side so as to move the beam a spot with higher effectiveness, and thereby a control with better responsiveness is achieved. |
