SCANNING OPTICAL SYSTEM AND CORRECTING OPTICAL SYSTEM FOR OPTICAL SCANNING DEVICE

摘要

PURPOSE: To realize a scanning optical system excellent in mass-productivity and capable of satisfactorily correct curvatures of image surfaces of main scanning and subscanning directions. CONSTITUTION: This device is constituted of optical scanning lenses 5 making a deflected luminous flux converge toward on a surface to be scanned as to a main scanning direction and a correcting optical system 6A image-forming the deflected luminous flux on the surface to be scanned 7 and also correcting curvatures of field in the main scanning and subscanning directions in cooperation with the optical scanning lenses 5 and, as to a subscanning direction, has a function making the deflection starting point 4 of the deflected luminous flux and the surface to be scanned 7 almost geometro-optical conjugate relation and a function making optical scannings on the surface to be scanned 7 almost equal speeds. The correcting optical system 6A is a long-length toroidal lens to be arranged between the optical scanning lenses 5 and the surface to be scanned 7 and includes a barrel-shape toroidal surface whose radius of curvature in the subscanning direction becomes small as an optical axis separates in the main scanning direction is as a concave lens surface.