| 摘要 |
PROBLEM TO BE SOLVED: To suppress jitters more securely while increasing flexibility of designing of lenses.SOLUTION: A scanning optical apparatus is equipped with: a light source 1; a first optical element (coupling lens 2) configured to convert light emitted from the light source 1 into a beam of light; a second optical element (cylindrical lens 4) configured to convert the beam of light having passed through the first optical element into a long linear image extending in a main scanning direction; a deflecting mirror (polygon mirror 5) configured to deflect the beam of light having passed through the second optical element in the main scanning direction; and a third optical element (fθ lens 6) configured to convert the beam of light having been deflected by the deflecting mirror into a spot-like image and focus it on a target surface to be scanned. The third optical element comprises a single lens having a pair of opposite lens surfaces, and each of the pair of lens surfaces has an aspheric shape in a main scanning plane to satisfy the formula 4. |
