| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner with high accuracy and low cost corresponding to the formation of high dot density of a recording medium by suppressing movement of an image forming position to the change of the ambient temperature at the time of using a plastic lens for a scanning lens system. SOLUTION: A combination lens system (3) includes the first optical device consisting of the material negative in the change of the refractive index to temperature and whose power is nearly 0, as at least one optical device except the optical device disposed by separating most from a light source. A scanning lens system (5) includes at least one second optical device consisting of the material negative in the change of the refractive index to temperature and having positive power.
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