HHG Beam Wavefront Characterization at 30 nm

For the purpose of characterization and improvement of the HHG (High-order Harmonics Generation) eXtreme Ultra-Violet (XUV) coherent beam at the wavelength 30 nm, we developed a unique wavefront sensor based on PDI (Point Diffraction Interferometer) technique. A simple self-referencing monolithic device produces interferometric pattern with encoded information about the wavefront profile of the measured beam. We describe the development, fabrication, and alignment of the sensor, as well as the obtained results and their interpretation.