Patent ID: 8179580

Claim:
An optical scanning device comprising: a light source; a scanning unit to deflect and scan a laser beam from the light source; an imaging optical system to focus the deflected and scanned laser beam to a scan-target surface; an electro-optic element, disposed in a light path between the light source and the scan-target surface, to electrically change a refractive index of an interior of the electro-optic element; a controller to control the refractive index of the interior of the electro-optic element and adjust deflection amount of the laser beam transmitted through the interior of the electro-optic element; and a positional shift detecting unit, disposed away from the light path from the electro-optic element to the scan-target surface, to detect a positional shift of an incident laser beam from an ideal position in a sub-scanning direction, an optical element disposed between the light source and the scan-target surface and which, while the laser beam is being focused on and scanned along the scan-target surface, splits the laser beam into a first laser beam directed to the positional shift detecting unit and a second laser beam directed to the scan-target surface, and wherein the controller adjusts a deflection amount of the laser beam from the electro-optic element based on a detection result obtained by the positional shift detecting unit and corrects a positional shift in the sub-scanning direction of the laser beam on the scan-target surface.