Schwarzschild soft-x-ray microscope for imaging of nonradiating objects

A soft-x-ray optical system based on multilayer mirrors was designed and fabricated for the production of magnified images of micro-objects with a spatial resolution of ~0.2 μm at a wavelength λ ≈ 20 nm. The system consists of a laser-produced plasma source, a condenser mirror, a 20× Schwarzschild objective, a filter set, and a detector. The quality of the x-ray optics and the precision of the system adjustment enabled us to achieve, for the first time to our knowledge, ~0.2-μm resolution using the full aperture (numerical aperture 0.2) of the objective and a single shot of a frequency-doubled Nd laser (pulse energy ~0.5 J, pulse duration ~1.5 ns).