Normal incidence optics for solar coronal imaging

Abstract

We have produced two new normal incidence soft x-ray telescope mirrors coated for lambda equals 63.5 angstrom wavelength: the first with a focal length f equals 1.5 m and a diameter of 25 cm for the Space Weather and Terrestrial Hazards (SWATH) satellite and the second (f equals 2 m, diameter 27.5 cm) for launch by sounding rocket (NIXT). We describe figuring and polishing of the mirror surfaces and deposition and testing of the multilayer coatings. Optimization of the mirror fabrication included grazing incidence x-ray reflectivity for quality control during polishing. In addition, the substrate and each metal layer of the Co-C multilayer coating were polished by an ion beam with in-situ roughness estimation. We explored the possibilities and limitations of telescopes for shorter wavelengths by coating several small mirrors covering the lambda equals 45 to 60 angstrom region at normal incidence and report on their performance.