Patent ID: 8169455

Claim:
An optical scanning device comprising: a vertical cavity surface emitting laser; a driving unit that controls modulation and driving of the vertical cavity surface emitting laser; a coupling optical system that couples a beam emitted from the vertical cavity surface emitting laser; an aperture that is configured to shape a beam spot diameter on a target surface; a deflecting unit that deflects a laser beam coming from the aperture; and a scanning optical system that guides the laser beam coming from the deflecting unit to the target surface, wherein the driving unit controls so as to satisfy conditions 1 and 2 below: P 1< P 100 condition 1 Wm>Ws condition 2 where, P 1 is light intensity obtained when a period of time corresponding to a minimum pixel unit (referred to as “T 1 ”) has elapsed after start of illumination, P 100 is light intensity obtained when a period of time 100 T 1 has elapsed after the start of illumination, Wm is a static beam spot diameter in a main-scanning direction, and Ws is a static beam spot diameter in a sub-scanning direction.