Optical scanner and image forming apparatus using the same

An optical scanner, which scans at least one scanned face by a light beam, includes a light source having a plurality of light emitting points, an optical system before a light deflector configured to form a plurality of light beams from the light source, a light deflector configured to deflect the light beams via the optical system before a light deflector and scan the deflected light beams, and a scanning optical system configured to focus on the scanned face the light beams deflected and scanned by a deflection face of the light deflector, the optical system before a light deflector including a first optical element having a negative power at least in a deflecting and scanning vertical direction, a second optical element having a power only in a deflecting and scanning direction and a third optical element having a power only in the deflecting and scanning vertical direction.