Optical scanning device and image forming apparatus

An optical scanning device which separately scans a plurality of scan target surfaces in a first direction with light, the optical scanning device comprising:

• a light source device configured to emit a first light beam and a second light beam corresponding to two different scan target surfaces of the plurality of scan target surfaces;
• an optical deflector including a reflection surface on which the first light beam and the second light beam emitted from the light source device are obliquely incident while being separated from each other in a second direction perpendicular to the first direction, and configured to deflect the first light beam and the second light beam;
• a scanning lens disposed on respective optical paths of the first light beam and the second light beam deflected by the optical deflector;
• and
• a branching optical element configured to transmit therethrough a major portion of the first light beam transmitted through the scanning lens and reflect a major portion of the second light beam transmitted through the scanning lens, wherein, when the first light beam and the second light beam deflected by the optical deflector are projected on a plane perpendicular to the first direction, the first light beam and the second light beam intersect between the optical deflector and the branching optical element.