OPTICAL SCANNING DEVICE AND IMAGE FORMING APPARATUS

摘要

A pre-deflector optical system includes an isolator arranged on an optical path of a light beam from a light source. The isolator has a first surface with different light transmittances depending on a polarization state of an incident light beam on a first side close to the light source and a second surface imparting an optical phase difference of a ¼ wavelength to the incident light beam on a second side. A deflector deflects the light beam passed through the pre-deflector optical system. A rotation mechanism rotates the isolator around its optical axis. A holding member holds the light source and the isolator in a predetermined positional relationship.