Optical scanning apparatus and image forming apparatus

An optical scanning apparatus comprising:

• a deflecting unit configured to scan first and second scanned surfaces in a main scanning direction by deflecting first and second light fluxes incident on a first deflecting surface at different angles with respect to a main scanning section in a sub-scanning section;
• and
• a first optical element including first and second optical portions which are configured to guide the first and second light fluxes deflected by the deflecting unit to the first and second scanned surfaces, respectively, wherein
• an incident surface of the first optical element projects most toward the deflecting unit at a position of a surface vertex on the incident surface in a sub-scanning section including the surface vertex,
• at least one of a first exit surface of the first optical portion and a second exit surface of the second optical portion is a sagittal tilt surface, and
• a distance between a surface vertex on the first exit surface and a surface vertex on the second exit surface in a sub-scanning section including an incident position of an axial ray is larger than a distance between a surface vertex on the first exit surface and a surface vertex on the second exit surface in a sub-scanning section including an incident position of an outermost off-axis ray.