| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical scanner by which focusing position deviation in main and sub scanning directions caused in accordance with the change of ambient temperature can be self-corrected in the entire system of an optical system, and a light spot having a small diameter can be formed on a surface to be scanned regardless of temperature change. SOLUTION: As to the optical scanner provided with a light source 1, the optical system 2 coupling a luminous flux from the light source to the successive optical system, an optical deflector 5 reflecting and deflecting the luminous flux from the coupling optical system by a deflecting and reflecting surface 5a, a scanning and image-forming optical system 6 condensing the deflected luminous flux by the optical deflector on a surface 7 to be scanned as the light spot, and a correction optical system 3 self-correcting the focusing position deviation of the light spot on the surface to be scanned caused in accordance with the ambient fluctuation; the system 3 has at least a pair of a resin lens 3a having an anamorphic surface having negative power both in the main scanning direction and in the sub-scanning direction and a glass lens 3b having the anamorphic surface having positive power at least in the sub-scanning direction, and is set between the system 2 and the surface 5a.
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