| 摘要 |
A scanning optical system includes a semiconductor laser, a polygonal mirror, which deflects a beam emitted from the semiconductor laser, an ftheta lens for converging the deflected beam onto an object surface, and a diffractive element located between the polygonal mirror and the ftheta lens. The diffractive element corrects a lateral chromatic aberration caused by the ftheta lens. The diffractive element is inclined such that the light source side edge of thereof is close to the polygon mirror and the other side edge is apart from the polygon mirror relative to the reference condition where the normal of the diffractive element is parallel to the optical axis of the ftheta lens. Further, the diffractive element is arranged such that a reference point, which is the center of the rotationally symmetrical diffractive surface, deviates from the optical axis of the ftheta lens in the direction away from the semiconductor laser.
|
