Scanning Optical System, Optical Scanning Device, and Image forming Device

摘要

A scanning optical system is provided with a light source device (1), a deflection optical system (5) that deflects the light flux from the light source device (1) to carry our a scan in a main-scanning direction (y), and a scanning and image-forming optical system (8) that forms the light flux deflected by the deflection optical system (5) into an image on a scanning surface (H). The scanning and image-forming optical system (8) includes at least a first lens (6). The scanning optical system satisfies a predetermined condition relating to a numerical aperture of a light flux entering the deflection optical system (8) in a sub-scanning direction (z), and a distance between the deflection optical system (5) and the first lens (6). The first lens (6) is a plastic lens made of a predetermined resin as a base material.