| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive, compact optical scanner that has high definition and reduces the curvature on the image surface of an incident optical system, and an image forming apparatus using the same.SOLUTION: An optical scanner includes: a light source that has a plurality of light emitting units; an incident optical system that has a collimator optical system for converting light beams from the light source, and a diaphragm for regulating the width of the light beams from the collimator optical system in one of the main scanning direction and sub scanning direction with a wider arrangement interval of the light emitting units; a deflector that is rotated around a rotation shaft parallel to the sub scanning direction and deflects the light beams from the incident optical system on a main scanning plane; and an imaging optical system that guides the light beams from the deflector to a scanning target surface. The collimator optical system includes a first optical element group and second optical element group composed of optical elements not including an aspherical surface and arranged from the light source side in order; when the distance from the incident surface of the second optical element group to the diaphragm is L, and the focal point distance of the incident optical system in one of the main and sub scanning directions with the wider arrangement interval of the light emitting units is f, the condition: 0.5<|L|/f<2 is satisfied. |
