| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanning optical system which dispenses with a mirror causing increase of a production cost and color slippage, further in which optical path length is not long and which can fully separate each laser beam till the arrangement spacing of a photosensitive drum without lowering scanning performance. SOLUTION: The scanning optical system is constituted so that the rear surface of a front side lens group 4a and front surfaces of rear side lens groups 4y, 4m, 4c, and 4k constituting an imaging optical system 4 are two-dimensional polynomial aspheric surfaces. Further the scanning optical system is constituted so that the rear surface of the front side lens group 4a is an optical surface of discontinuous step-shape having different height in a main scanning direction. COPYRIGHT: (C)2004,JPO
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