Patent ID: 8115794

Claim:
An optical scanning device comprising: a light source of surface emitting lasers arrayed two-dimensionally that emits a plurality of light beams; a first optical system that guides the light beams from the light source in a first direction; a deflection unit having a plurality of deflection surfaces that receive the light beams guided by the first optical system and deflect the light beams in a second direction; and a second optical system that guides the light beams deflected by the deflection unit toward a surface to be scanned, wherein when pixel density is taken to be n, number of the light beams is taken to be b, and number of the deflection surfaces is taken to be p, a spatial frequency S, denoted by: S=1/((25.4/n)×b×p), is greater than or equal to 0.7 and less than or equal to 2.0, and when spacing between ends in a sub-scanning direction of a scanning line formed by one scan by the deflection unit is taken to be L 1 , and spacing between all progressive scanning lines at the surface to be scanned is taken to be L 2 , then: L 1 >(k−1)×L 2 is satisfied, where k is a total number of light emitting points of a light source.