| 摘要 |
PURPOSE:To reduce the cost and to improve the performance by providing a correction lens consisting of an incident surface having power in the scanning direction and the sub-scanning direction, and an emitting surface which is positioned at the opposite side of said incident surface, formed symmetrically against the scanning direction and has power in the scanning direction. CONSTITUTION:A correction lens 10 consists of an incident surface 15 which has power in the scanning direction and the sub-scanning direction (direction being orthogonal to the scanning direction) and goes to a rotation symmetrical curved surface 14 drawn in the sub-scanning direction centering around a rotation symmetrical axis 13 being parallel to the scanning direction, and an emitting surface which is positioned at the opposite side to said incident surface 15, formed symmetrically against the scanning direction and has power in the scanning direction. Accordingly, a correction of an ftheta characteristic, and a correction of a curvature of a sagittal image surface and a meridional image surface can be executed. In such a way, the correction of the ftheta characteristic can be executed by an optical means without using an electrical means, therefore, a simple structure having a high performance is obtained at a low cost. |
