| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an illumination optical system capable of attaining the formation of higher NA and the enlargement of a σ value variable extent by consisting of a smaller number of lenses and the smaller scale while positioning a recondensing position where light energy density is increased outside the lens and satisfying a structural constraint and the constraint of the diameter of an optical material. <P>SOLUTION: In the illumination optical system, a reimaging optical system is an exit telecentric optical system where principle rays of off-axis luminous flux are nearly collimated in an image cavity, and the system is provided with a 1st lens group having positive power, a 2nd lens group having negative power and a 3rd lens group having positive power in this order from a light incident side. Further, By arranging a concave lens on the light exit side of the 2nd lens group, and also, arranging a convex lens on the light incident side of the 3rd lens group, an intersection position where the principle ray of the off-axis luminous flux crosses the optical axis exists between the 2nd lens group and the 3rd lens group. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
