| 摘要 |
An illumination optical system includes, in order from a light source side a collector lens, a field stop, a field lens having positive power, an aperture stop, and a collective lens having positive power. The illumination optical system is a substantially both-side telecentric optical system between the field stop and a sample surface, and satisfies the following conditional expressions where DFS indicates a diameter of the field stop, &bgr; indicates a magnification from the sample surface to the field stop, and NA indicates a numerical aperture on the sample surface side of the illumination optical system. 15≧DFS/&bgr;≧9   (1) 0.85≧NA≧0.5   (2)
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