To prevent the positional deviation of light beams corresponding to each color in a scanning direction and to simplify the constitution of an optical system including an fθ lens.
Each of the light beams L emitted from semiconductor lasers (120A) to 120D reaches each of the reflection surfaces 322 of a polygon mirror 320. Each of the light beams L reflected by each of the surfaces 322 is converged mainly in a vertical direction (subscanning direction) by a 1st fθ lens 400 and made incident on a 2nd fθ lend 500. Each of the light beams L is converged only in a horizontal direction (main scanning direction) by the action of the lens 500 constituted of a single member made of single material and emitted, made incident on 3rd fθ lenses 600A to 600D through a mirror part, then reaches each photoreceptor drum.
SUZUKI YASUSHI
MIKAJIRI SUSUMU
