Patent ID: 7154651

Claim:
A multi-beam optical scanning device, comprising: a light source having a plurality of emission points that emit a bundle of rays; a first optical system that couples the bundle of rays emitted from the light source into a bundle of diverging rays; a second optical system that condenses the bundle of diverging rays from the first optical system into a substantially linear state extending along a main scanning direction; a light deflector that has a deflection surface arranged close to where the bundle of linear rays is condensed, wherein the bundle of linear rays is deflected by said deflection surface; an aperture stop arranged between the first optical system and the light deflector; a third optical system that condenses the deflected bundle of rays onto a surface to be scanned as a plurality of light spots; wherein the third optical system has at least one resin imaging element; the second optical system has a plurality of imaging elements including a resin imaging element and a glass imaging element; at least one of the resin imaging elements of the second optical system has a negative power in a sub scanning direction and a surface configuration that is arranged to effectively compensate for a change in field curvature caused by a temperature change in at least one of a support member of the first optical system and the resin imaging element of the third optical system; the second optical system as a whole has a positive power in the main scanning direction; at least one of the resin imaging elements of the second optical system has a power in the main scanning direction, and is positioned so that a beam waist in the main scanning direction is substantially positioned on the surface to be scanned; and said at least one of the imaging elements of the second optical system has power only in the main scanning direction.