| 摘要 |
PROBLEM TO BE SOLVED: To provide an illumination optical system capable of producing converted illumination such as zonal illumination, quadruple illumination while reducing an optical loss at an aperture to a small amount. SOLUTION: This illumination optical system includes angled optical flux forming means 4, 5 for converting an optical flux from a light source 1 into a plurality of optical fluxes having angle components, optical flux shape converting means 6, 7 for forming, for example, zonal optical intensity distribution based on the optical fluxes, an optical integrator 8 which receives the optical fluxes to form a secondary light source having a zonal optical intensity distribution, and a light introducing optical system 10 for introducing the optical fluxes from the optical integrator 8 into a mask 11.
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