| 摘要 |
PURPOSE:To realize mass-production and to reduce the extent of curvature of an image surface by using one plastic lens as a lens for scanning and, curving a meridional image surface and a sagittal image surface closer to a lens side than a Gaussian image surface and the sagittal image surface closer to the lens side than the meridional image surface. CONSTITUTION:An optical system which scans and focuses the light beam of a laser 10, etc., uses one plastic lens as the scanning lens for converging the light. This plastic lens 13 is so shaped that the curvature of the meridional image surface and the curvature of the sagittal image surface within the in-use scanning angle of this lens is closer to the lens side than curvature of the Gaussian image surface except on the optical axis and the curvature of the sagittal image surface is closer to the lens side than the curvature of the meridional image surface except on the optical axis.
|
