| 摘要 |
PROBLEM TO BE SOLVED: To simplify the assembling of a cylindrical lens and to prevent the relative positions of the cylindrical lens and an image formation lens from being changed. SOLUTION: Laser light generated from a light source 10 is linearly converged on the reflection face of a rotary polygon mirror 12 by the cylindrical lens 11 and an image of the converged light is formed on a photosensitive body by the image formation lens 13. The lens 13 is a plastic lens molded unitedly with a seating 15 for assembling the lens 11. Thereby, it is unnecessary for preparing a step difference or the like for allowing the generatrix 11a of the lens 11 to coincide with the generatrix 13a of the lens 13 on the bottom wall 14a of a casing 14, the assembling of the lens 11 is simple and the relative positions of the lenses 11, 13 are not changed by the thermal distortion of the casing 14. |
