OPTICAL SCANNER

PROBLEM TO BE SOLVED: To provide an optical scanning device which can be used for various apparatus for scanning a light beam on an image formation surface away from a light source by a fixed distance to form a dot image or conversely, optically reading an image of a document and can especially embody high resolution scanning stably. SOLUTION: The above optical scanning device comprises a light source part 1 for emitting a parallel beam 9, a cylindrical lens 2 for focusing the beam in the sub-scanning direction, a deflector 3 for deflecting the beam in the main scanning direction, and image forming toroidal lens 5-7 for imaging the deflected beams and focusing to form a dot image on a photosensitive drum 8. The image forming toroidal lens 5-7 have high aperture rate and a function of compensating for the inclination of a mirror finished surface of the deflector 3. The device can perform high speed scanning with high resolution and is utilized in a laser printer so as to realize high image quality and high speed printing.