| 摘要 |
PURPOSE:To make a scan at a wide view angle while having high optical performance by constituting a scanning lens system so that at least two lenses having toric surfaces are provided. CONSTITUTION:The total positive refracting power of the scanning lens system 67 is divided to two lenses, i.e. 1st and 2nd lenses 6 and 7 to reduce the center thickness of each lens. Further, each lens is installed having its concave surface on the side of a deflector in main scanning section to excellently compensate the meridional curvature of field, and a difference due to a difference in the transmissivity of luminous flux passing through the scanning lens system i.e. a difference due to a difference in scanning angle is reduced to uniform the transmissivity. Then the lens shapes of the 1st lens 6 and 2nd lens 7, refracting power of each lens surface, etc., are set under specific conditions to scan an object surface while maintaining the excellent optical performance. |
