| 摘要 |
PURPOSE:To reduce the variance of light intensity on a surface to be scanned by deflecting the optical beam from a laser light source by rotation of a polygonal mirror and cancelling the change of the angle of incidence due to rotation of the polygonal mirror by adjustment of inclination of a plane mirror when the surface to be scanned is irradiated through an ftheta lens and the plane mirror. CONSTITUTION:An ftheta lens 12 is provided to face a polygonal mirror 10, and the optical beam passing this lens 12 is reflected on a plane mirror 16 and is irradiated to a surface 14 to be scanned. A light scanning optical system is constituted in this manner, and an optical beam LB from the laser light source is irradiated to the rotating face of the polygonal mirror 10 and the reflected beam LB is made incident on the ftheta lens 12, and at this time, the beam LB incident on the lens 12 is shaked at -theta0-+theta0 by rotation of the mirror 10. The angle alpha of inclination of a reflection mirror 16 inclined to an optical axis AX behind the lens 12 is adjusted to cancel the angle theta0 of shake, thereby controlling the beam LB reaching the surface 14 to be scanned to a certain angle. Thus, light scanning is improved. |
