| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanning optical system capable of suppressing a scanning line from curving on a surface to be scanned, even in the case an incident angle in a subscanning direction on a polygon mirror is other than 0 deg.. SOLUTION: The scanning optical system is provided with a light source part 10 for emitting two luminous fluxes, the polygon mirror 20, a scanning lens 30 constituted of a 1st lens 31 and a 2nd lens 32, and a correction lens 50, and a beam spot is formed on a photoreceptor drum 60. All the lens surfaces of the scanning lens 30 are made to be rotation-symmetrical, as for the surface on the polygon mirror side of the correction lens 50, the cross section in the subscanning direction is formed to be asymmetrical with reference to the optical axis, and also, the surface is formed to an aspherical surface where the sagging quantity is expressed by a two-dimensional polynomial.
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