Lighting for EUV projection lithography

An illumination optics for EUV projection lithography for illuminating an illumination field with EUV-useful light (12) of an EUV light source (2) has an optical assembly (13) emitted for transferring the EUV radiation of the light source (2) in an intermediate focus (Z). The optical assembly (13) has a in the beam path of the EUV radiation (12) arranged photon sieve (16). The result is improved with regard to their stability in the use of EUV light sources illumination optics.