Schwarzschild objectives are increasingly used as imaging optics in the EUV spectral region because of their large aperture, high mechanical stability and they are free of chromatic aberrations. The use of such objectives is manifold starting from applications for EUV lithography, fundamental research using Synchrotron radiation to imaging optics for X-ray lasers.
A Schwarzschild objective consists of a convex and a concave multilayer coated
mirror. Depending on the optical path of the objective it can be used for the
magnification (e.g. microscopy) or demagnification (e.g. lithography) of
objects and structures.
- Hence, substrate surface deformation by gravitation, intrinsic mechanical stresses of the coating and the mechanical holder has to be taken into account and – if necessary – corrected properly.
- Athermical design
- Use of a polymer-free joining technique for optical elements on the basis of a soldering process to center components with micrometer accuracy.