IMAGING OPTICAL UNIT

An imaging optical unit comprises a plurality of mirrors for imaging an object field in an object plane into an image field in an image plane. An image-side numerical aperture is greater than 0.55. A ratio between an object/image offset and a meridional transverse direction is at least 0.5. A ratio...

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Bibliographische Detailangaben
Hauptverfasser: ROSTALSKI, Hans-Jürgen, MENKE, Christoph, MÜNZ, Holger
Format: Patent
Sprache:eng ; fre ; ger
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Beschreibung
Zusammenfassung:An imaging optical unit comprises a plurality of mirrors for imaging an object field in an object plane into an image field in an image plane. An image-side numerical aperture is greater than 0.55. A ratio between an object/image offset and a meridional transverse direction is at least 0.5. A ratio between a working distance between the object plane and a reflection portion, closest to the object plane, of one of the mirrors and the meridional transverse dimension is at least 0.05. The working distance is at least 270 mm. This can yield an imaging optical unit, the use of which is relatively manageable in a projection exposure apparatus, such as for EUV projection lithography.