| 摘要 |
PROBLEM TO BE SOLVED: To effectively correct and reduce the bend of a scanning line, by determining the tilt in the sub-scanning cross section on a beam incident position of a correction refractive surface in accordance with the incident position so as to correct the bent of a scanning line of the beam. SOLUTION: The peripheral part of light beam is cut off by passing through the opening part of an aperture 20 and the beam is formed to have a proper cross sectional shape. The formed beam is converged in the corresponding direction of scanning by means of a cylindrical lens 25. A reflected beam by a deflection/reflection surface is deflected at a constant angular velocity accompanying the constant speed revolution of a polygon mirror 30, transmitted through lenses 41-43, converged on a surface 50 to be scanned by lens action as a light spot and optically scans the surface 50 to be scanned. In this case, any lens surface of the lenses 41-43 of the scanning image forming optical system is made to be a correction refractive surface, the tilt of the correction refractive surface in the sub-scanning cross section at the incident position of at least one beam from among plural incident beams is adjusted and the bend of scanning line of the beam is corrected. |
