Abstract: In an overfilled optical scanner in which a plurality of light beams are used, a uniform luminous-energy distribution is achieved on a scanning plane to be scanned. The optical scanner includes: a light source 3 for producing a first light beam L1 and a second light beam L2; a polygon mirror; a first image formation optical system for leading the light beams L1 and L2 to a deflecting plane of the polygon mirror and for forming, on the deflecting plane, a line image whose width is greater than the plane width of the deflecting plane; and a second image formation optical system for leading the light beams L1 and L2 from the polygon mirror to the scanning plane of a photosensitive drum and forming an image on the scanning plane. The first image formation optical system is adjusted so that the optical axes A1 and A2 of the first and second light beams L1 and L2 are approximately symmetrical about the optical axis A0 of the first image formation optical system.

Abstract: In an overfilled optical scanner in which a plurality of light beams are used, a uniform luminous-energy distribution is achieved on a scanning plane to be scanned. The optical scanner includes: a light source 3 for producing a first light beam L1 and a second light beam L2; a polygon mirror; a first image formation optical system for leading the light beams L1 and L2 to a deflecting plane of the polygon mirror and for forming, on the deflecting plane, a line image whose width is greater than the plane width of the deflecting plane; and a second image formation optical system for leading the light beams L1 and L2 from the polygon mirror to the scanning plane of a photosensitive drum and forming an image on the scanning plane. The first image formation optical system is adjusted so that the optical axes A1 and A2 of the first and second light beams L1 and L2 are approximately symmetrical about the optical axis A0 of the first image formation optical system.