| 摘要 |
PURPOSE:To correct deviations of the optical beam diameter and the scanning speed on a projection face, by using a parabolic mirror and a cylindrical lens to condense the light on a plane parallel to the scanning direction and on a plane vertical to it independently of each other. CONSTITUTION:The beam deflected by a rotary polyhedral mirror 2 is reflected by a half mirror 3 and is reflected again by a parabolic mirror 11 and passes through a cylindrical lens 10 and is condensed onto a projection face 7. The projection face 7 is placed in respective focus positions of the parabolic mirror 11 and the cylindrical lens 10, and a focal length fP of the parabolic mirror 11 and a focal length fC of the cylindrical lens 10 satisfy relation fP>fC. The light is condensed on a plane P parallel to the scanning direction by the parabolic mirror 11, and the light is condensed on a plane vertical to it by the cylindrical lens 10, and thus, scanning of less deviation is performed up to a high angle. |
