| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanning optical system in which ghost light is sufficiently eliminated without setting the shift value and the tilt value of the reference axis of the optical plane of a lens face large. SOLUTION: The scanning optical system is so constituted that a scanning lens 4 for focusing a laser beam dynamically deflected with a polygon mirror 3 on an object plane to be scanned is composed of a first plastic lens 4a and a second plastic lens 4b. Further, the scanning optical system is so constituted that the original point A of a lens face of the first plastic lens 4a is located at the opposite side of the original point B of the other lens face across a principal axis Ax in a subscanning direction. Further, the scanning optical system is so composed that the original points C and D of both lens faces of the second plastic lens 4b are located at the side on which the original point B of the rear face of the first plastic lens 4a is present, between both sides across the principal axis Ax in the subscanning direction. COPYRIGHT: (C)2004,JPO&NCIPI
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