| 摘要 |
There is provided a scanning optical system which includes a light source, a line-like image forming optical system, a polygonal mirror, and an imaging optical system. The line-like image forming optical system forms a line-like image extending in the main scanning direction in the vicinity of a reflective surface of the polygonal mirror, and if the number of reflective surfaces of the polygonal mirror is less than or equal to six and if |m|>1.85, the following condition (1) is satisfied: <?in-line-formulae description="In-line Formulae" end="lead"?>r<5 COS(w/2f)/[2|m|{1- cos(w/2f)}] (1)<?in-line-formulae description="In-line Formulae" end="tail"?> where r represents a radius of an inscribed circle of the polygonal mirror, m represents a lateral magnification of the imaging optical system in the auxiliary scanning direction, f represents a focal length of the imaging optical system in the main scanning direction, and w represents half of a scanning width. |
