Abstract
The tangential curvature of actively bent X-ray mirrors at synchrotron radiation and X-ray free-electron laser (XFEL) facilities is typically only changed every few hours or even days. This operation can take tens of minutes for active optics with multiple bending actuators and often requires expert guidance using in situ monitoring devices. Hence, the dynamic performance of active X-ray optics for synchrotron beamlines has historically not been exploited. This is in stark contrast to many other scientific fields. However, many areas of synchrotron radiation and XFEL science, including macromolecular crystallography, could greatly benefit from the ability to change the size and shape of the X-ray beam rapidly and continuously. The advantages of this innovative approach are twofold: a large reduction in the dead time required to change the size of the X-ray beam for different-sized samples and the possibility of making multiple changes to the beam during the measurement of a single sample. In the preceding paper [Part I; Alcock, Nistea, Signorato & Sawhney (2019), J.Synchrotron Rad. 26, 36-44], which accompanies this article, high-speed visible-light Fizeau interferometry was used to identify the factors which influence the dynamic bending behaviour of piezoelectric bimorph deformable X-ray mirrors. Building upon this ex situ metrology study, provided here is the first synchrotron radiation beamline implementation of high-speed adaptive X-ray optics using two bimorphs operating as a Kirkpatrick-Baez pair. With optimized substrates, novel opto-mechanical holders and a next-generation high-voltage power supply, the size of an X-ray beam was rapidly and repeatedly switched in <10 s. Of equal importance, it is also shown that compensation of piezoelectric creep ensures that the X-ray beam size remains stable for more than 1 h after making a major change. The era of high-speed adaptive X-ray optics for synchrotron radiation and XFEL beamlines has begun.
Highlights
Active and adaptive optics have routinely been used for several decades by many scientific disciplines, including astronomy, laser physics and microscopy
Adaptive optics for ground-based astronomy are driven in closed loop at high speed using realtime feedback to correct wavefront aberrations caused by atmospheric turbulence
We have provided the first demonstration that piezoelectric bimorph deformable X-ray mirrors can be operated in open loop as high-speed adaptive optics for synchrotron and X-ray free-electron laser (XFEL) applications without the necessity for continuous real-time feedback
Summary
Active and adaptive optics have routinely been used for several decades by many scientific disciplines, including astronomy, laser physics and microscopy. Stick/slip behaviour of the substrate mounted in a non-ideal holder can cause the curvature of the mirror to change when a voltage is applied to individual piezo electrodes or collectively to all (Vannoni et al, 2016) Such waiting times are acceptable when beamlines operate with quasi-static optics, tuned to a known set point and left untouched for prolonged periods. The positive outcome of this ex situ metrology study brought us naturally to the step: install Mirror 3 on a synchrotron beamline at Diamond Light Source and confirm that the X-ray beam size can be rapidly changed and stabilized in a repeatable manner, thereby enabling scientific users to access this functionality during routine beamline operation
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