| 摘要 |
<p>The invention relates to an optical Element for forming an arc-shaped field in a field plane of an illumination system for wavelengths ≤ 193 nm, preferably ≤ 126 nm, especially EUV-wavelengths, wherein: the arc-shaped field has an axis of symmetry and the field plane is defined by a vector in y-direction, which is in parallel to the axis of symmetry and a vector in x-direction, which is orthogonal to the axis of symmetry, said optical element comprises, a plurality of mirror surfaces each (12.1, 12.2, 12.3)comprising an array of aspherical reflecting elements wherein, said array of aspherical reflecting elements comprise a plurality of cylindrical mirrors with aspheric curvature in x-direction and said plurality of mirror surfaces are forming a nested mirror, wherein (10) two adjacent mirror surfaces have a spacing dspace.</p> |
