| 摘要 |
<p>A scanning optical system includes a light source, an optical deflector for deflecting a laser beam emitted from the light source, a first optical element for collimating the laser beam emitted from the light source into a parallel beam, a second optical element for focusing the parallel beam collimated by the first optical element to the optical deflector and making the parallel beam incident on the optical deflector, a third optical element for focusing the laser beam deflected by a deflection plane of the optical deflector onto a target irradiation surface. In a subscanning section of the scanning optical system, the following conditions are satisfied. An optical axis of the first optical element and an optical axis of the second optical element are parallelly decentered from each other. The second optical element and the third optical element are decentered from a central axis of the scanning optical system. The optical axis of the second optical element crosses the central axis of the scanning optical system near the optical deflector. The optical axis of the first optical element crosses the central axis of the scanning optical system near the second optical element. A central point of the third optical element is positioned on an extended line of the optical axis of the second optical element. The optical axis of the second optical element and a normal of the deflection plane of the optical deflector are not parallel to each other. <IMAGE></p> |
