| 摘要 |
PURPOSE:To increase an angle of field in a main scanning direction while maintaining image formation characteristics and a surface tilt correcting function by arranging a cylindrical lens which has no refracting power along a scanning surface and the 2nd lens with a toric surface. CONSTITUTION:A scanning image formation optical system 3 which forms the image of light beam flux B reflected and deflected by a deflector 4 on a body 6 to be scanned consists of the cylindrical lens G1 which has no refracting power along the scanning surface and the 2nd lens G2 which has the toric surface in order from the side of the deflector 4. Namely, the cylindrical surface and toric surface of the cylindrical lens G1 are provided to different lenses although this optical system has the simple constitution where the lens on the side of the deflector is they cylindrical lens G1 having refracting power only at right angles to the scanning surface. Consequently, the image formation characteristics in the direction crossing the scanning surface at right angles is maintained excellently over a considerably wide range and the degree of freedom of design is increased. |
