| 摘要 |
PROBLEM TO BE SOLVED: To obtain a scanning optical system having a reduced number of optical parts and capable of improving yield, and to provide an image forming device using the same. SOLUTION: The scanning optical system has a light source means 1, an incident optical means 2 for condensing a pencil of light injected from the light source means, a deflection means 4 for deflecting the pencil of light so that the pencil of light guided from the incident optical means scans a scanning surface 6, and an image-forming optical means 5 for condensing the pencil of light deflected by the deflection means on the scanning surface. In the scanning optical system, the expression: 0.8≤(dS/dX)/(dM/dX)≤1.2 is satisfied, wherein dM represents the displacement of the focus position on the main scanning section in the scanning surface when the light source means or the incident optical means is displaced by dX in the direction of the optical axis, and dS represents the displacement of the focus position on the sub-scanning section in the scanning surface. COPYRIGHT: (C)2007,JPO&INPIT
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