Development of thin deformable X-ray mirrors for synchrotron applications

The future of synchrotron light sources will bring diffraction-limited X-ray beams, providing high brightness and coherent wavefronts to an increasing number of beamline endstations around the world. In order to engineer coherent wavefronts and harness the high power densities, we need to develop X-ray deformable mirrors that can control the wavefront with high precision (< 5 nm-rms), can steer the beam at high speed (> 1 kHz) and be compatible with ultra-high vacuum environments. We show that deformable mirrors made on industry-grade silicon wafers, borrowing a technological platform developed for space X-ray telescopes, could potentially be used for synchrotron applications, with residual figure error of about 10 nm-rms that can be actuated to cause 100 nm PV local deformation and operation at frequencies up to 10 kHz. We also show that we can use machine learning techniques to improve their performance in operation, reducing the effects of drift and hysteresis, and make the device easier to calibrate periodically. We discuss future next steps such as stress compensation, fine substrate figuring and integrating electronics that would make them ready for use in experimental endstations at synchrotron beamlines.