| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent performance in terms of the curvature of field, fθcharacteristics and the curvature of a scanning line by constituting a 2nd image-formation optical system only of one curved surface mirror without requiring an optical path separation means such as a half mirror, and to obtain an excellent spot where wave aberration is corrected. SOLUTION: A reflecting mirror 4, a polygon mirror 5 and the curved surface mirror 7 are arranged at positions different in a subscanning direction so that luminous flux from the mirror 4 is made obliquely incident on a surface including the normal of the deflection surface of the mirror 5 and parallel with a main scanning direction, and the luminous flux from the mirror 5 is made obliquely incident on a surface including a normal at the apex of the mirror 7 and parallel with the main scanning direction. A conditional expression; 1.20<θM/θP<1.657 holds. Where, an angle formed by the normal of the deflection surface with the luminous flux isθP, and an angle formed by the normal at the apex of the mirror 7 with the luminous flux from the deflection surface isθM. COPYRIGHT: (C)2004,JPO
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