| 摘要 |
An illumination optical system includes a light source section for emitting a beam of substantially parallel rays, a field lens for collecting the beam of substantially parallel rays, a condenser lens for introducing the beam of rays collected by the field lens onto an illumination target surface, and an aperture stop disposed at an entrance-side focal position of the condenser lens. The aperture stop and the light source are in conjugate positional relationship via the collector lens and the field lens. An optical element having different characteristics between the central region and the outer region is arranged in a path of the substantially parallel rays at a position satisfying the condition: <?in-line-formulae description="In-line Formulae" end="lead"?>0.03<|L/f<SUB>CD</SUB>|<0.4<?in-line-formulae description="In-line Formulae" end="tail"?> where F<SUB>CD </SUB>is a focal length of the condenser lens and L is a distance from the illumination target surface to a position that is, of positions on which the optical element is projected, closest to the illumination target surface.
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