| 摘要 |
PURPOSE:To improve a detection accuracy by dislocating and disposing a detecting element in an opposite direction to the rotating direction of a scanning mirror from a center line connecting scanning mirror and a lens on the circumference whose center is the rotating axis of the scanning mirror. CONSTITUTION:The detecting element 4a is dislocated and disposed on the center line 6 on the circumference whose center is the rotating axis 5 of the scanning mirror 3 and the dislocating direction is opposite to the rotating direction of the scanning mirror, namely, supposing the rotating direction of the scanning mirror is clockwise, the detecting element 4a is dislocated and disposed in a counterclockwise direction from the center line 6. When the detecting element is dislocated and disposed from the center line, an optical system efficient characteristic is asymmetric with respect to the center line. Further, dislocating the element 49 in an opposite direction to the rotating direction of the scanning mirror, the change ratio of the optical system efficiency is suppressed low in the front side of a scanning visual field, accordingly, the influence of a scanning noise in the visual field is reduced. |
