Toward the fabrication of a 5 μm resolution Wolter microscope for the National Ignition Facility

Advancements in computer-controlled polishing, metrology, and replication have led to a x-ray mirror fabrication
process that is capable of producing high-resolution Wolter microscopes. The mirror is a nickel-cobalt
replicated full-shell mirror that was electroformed from a finely figured and polished mandrel. This mandrel
was designed and fabricated for a 8 m source-to-detector distance microscope, with 10× magnification. A
computer controlled polishing process corrected the low-frequency mandrel figure to < 2.0 nm RMS error.
The mandrel design was optimized to reduce shell distortions that occur mainly < 20 mm from the shell ends.
This design, in combination with improved replication tooling design and refined bath parameters informed
by a detailed COMSOL model, have led to reductions in replication errors in the mirror shell. X-ray tests
performed on a pair of mirror shells replicated from the mandrel have demonstrated < 10 μm FWHM source
plane imaging resolution. Here we discuss the development process, highlight results from metrology and
x-ray testing, and define a path for achieving 5 μm FWHM resolution.