Multi-beam optical scanning apparatus and image forming apparatus

摘要

A multi-beam optical scanning apparatus includes a semiconductor laser array slanted relative to a sub-scanning direction and emitting a plurality of optical beams; a coupling lens converting a shape of each optical beam emitted from the semiconductor laser array; and an aperture with an opening having a size of AmxAs, arranged after the coupling lens in a direction in which the optical beam progresses, where Am is a dimension of the opening in a main scanning direction and As is a dimension of the opening in the sub-scanning direction. When a length in the main scanning direction of a contour line defined by 1/e<2 >strength of a maximum strength of an optical beam at the position of the aperture is Lm, and a length in the sub-scanning direction of the contour line defined by 1/e<2 >strength of the maximum strength of the optical beam at the position of the aperture is Ls, the following conditional expressions are satisfied: Am<Lm (1), and Ls/Lmx0.3<As/Am<Ls/Lmx1.7 (2).