| 摘要 |
A scanning optical apparatus includes a light source, a deflecting element for deflecting a beam of light emitted from the light source, and an optical device for causing the beam to be imaged into a linear shape long in the main scanning direction on the deflecting surface of the deflecting element. The device comprises a first optical element and a second optical element, and a third optical element for causing the deflected beam of light to be imaged into a spot-like shape on a surface to be scanned. The third element includes a single lens, the opposite lens surfaces of which both include a toric surface of an aspherical surface shape in the main scanning plane, the curvatures of the opposite lens surfaces in the sub scanning plane being continuously varied from the on-axis toward the off-axis in the lens's effective portion. |
