| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner which performs a stable optical scanning without inviting cost increase. SOLUTION: The optical scanner is provided with a light source, a coupling lens, a linear image forming lens 4, a polygon mirror and a scanning optical system, where the emission face of the linear image forming lens 4 is a diffraction face, on which straight grooves are formed, stretched in a direction in which a wavelength deviation is large. Thus, the diffraction effect which reduces the influence of the wavelength deviation on a beam waist position is selectively given to scanning light. The shift in the beam waist position is reduced, both in the main scanning direction and the subscanning direction. As a result, stable optical scanning is possible without inviting cost increase. COPYRIGHT: (C)2009,JPO&INPIT
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