Hartmann wavefront sensor in the EUV and hard X-ray range for source metrology and beamline optimization (Conference Presentation)

Abstract

Emergence of ultrafast EUV to X-ray sources, Free Electron Laser, High harmonic generation, betatron and Compton, has opened new paradigms in physical, chemical, biological and medical sciences by either producing ultrahigh intensities or for ultrafast imaging or by enabling pump-probe experiments at new timescales. Most of these experiments require an excellent or at least a properly defined wavefront (WF). A number of WF sensing techniques have been proposed in the X-Rays, including grating-based interferometry, speckle tracking, pencil beam deflectometry, or curvature sensors. Among these techniques, Hartmann WF sensing demonstrated a number of advantages, such as insensitivity to vibrations, achromaticity and very large dynamic range. Furthermore, the phase and intensity maps are directly retrieve and nearly instantaneously without the use of complex and long algorithms. Imagine Optic developed EUV to X-ray WF sensors since more than 15 years taking benefit of decades of experience in the visible range. We will show several experiments using our EUV sensors for metrology and optimization of ultrafast EUV sources. We recently developed a Hartmann sensor in the 5 - 25keV range. The device is based on a custom scintillator-to-detector optical relay system, as well as on an optimal Hartmann array geometry, providing 20µm spatial WF sampling resolution, over a 3x3 mm² pupil. We show the results of first experiments on a synchrotron beamline at 10 keV, achieving 4pm WF repeatability.