Hans-Jürgen Mann

Reflective high-NA projection lenses

Dioptric systems are usually the first choice for the design of an optical system, e.g. a projection lens or a microscope. But in some cases refractive designs suffer from serious drawbacks like chromatic aberration or material problems (cost, quality, absorption, birefringence, etc.). In such cases reflective systems are an attractive alternative. Reflective systems can be subdivided into two classes: on one hand there are systems with central pupil obscuration, e.g. reflective microscopes or telescopes in astronomy, which have a high aperture but only a small field size, on the other hand there are unobscured systems, e.g. reflective relay systems or EUV projection lenses, which have a large field but only small aperture. By the combination of an unobscured and an obscured mirror system one obtains systems with large field and high numerical aperture. We present new designs, which prove this design principle.