Speaker
Description
The upgrade of the Advanced Light Source will provide an almost fully coherent soft x-ray beam to the
users, increasing the ALS brightness by 100x. Such a beam places extraordinary demands on every
beamline optical element. To maintain the beam’s coherence and wavefront properties in the presence of
high power loads, mechanical drift, and manufacturing errors, we have developed a suite of technologies
to monitor, preserve, and correct the wavefront dynamically, to ensure optimal performance in routine
operation.
We will present recent results on cryo-cooled mirrors [1], where our highest-power mirrors will be cryocooled
silicon to reach the 125K zero-point of thermal expansion, and be supported from one side in a
unique, cantilevered design. To enable continuous monitoring of the beam quality, we have developed a
fast, intermittent, wavefront sensor [2] based on shearing interferometer placed after the final focusing
mirror. The device uses a binary amplitude reflection grating used at glancing incidence in a conical
geometry. To compensate for eventual aberrations, each new beamline design includes a pre-figured
adaptive x-ray optic to correct wavefront errors and restore optimal beam properties. We have studied the
dynamic behavior of piezo-bimorph adaptive mirrors, and apply machine learning to overcome hysteresis
and creep [3]. To ensure diffraction-limited performance during regular user operation, we recently
deployed an automated alignment method for the whole photon transport system based on bayesian
optimization [4]. We will also present our work on the design and simulation of high-coherent-flux
beamlines, including efforts toward the creation of effective digital twins. And finally, we will present some
potential applications of wavefront engineering.
[1] Experimental testing of a prototype cantilevered liquid-nitrogen-cooled silicon mirror
G. Cutler, D. Cocco, B. Bentley, M. Cervantes, P. Chavez, J. Chrzan, S. DiMaggio, R. Hussey, J.
Ilmberger, J. Lindsay, E. Lizotte, K. McCombs, S. Morton, G. Paulovits, K. Pearson, C. Redding, N.
Smith, K. Tokunaga, D. Zehm, E. DiMasi and H. Padmore Journal of Synchrotron Radiation 30, 1 (2023)
https://doi.org/10.1107/S1600577522010700
[2] X-ray wavefront sensor development at the Advanced Light Source
K. A Goldberg, A. Wojdyla, D. Bryant, X. Shi, L. Rebuffi, M. Frith, M. Highland, L. Assoufid, Y. Ichii, T.
Inoue, K. Yamauchi; Proceedings of SPIE 12695, Advances in Metrology for X-Ray and EUV Optics X;
126950B (2023) https://doi.org/10.1117/12.2679136
[3] Data-driven modeling and control of an X-ray bimorph adaptive mirror
G. Gunjala, A. Wojdyla, K. A. Goldberg, Z. Qiao, X. Shi, L. Assoufid and L. Waller;
J. Synchrotron Rad. (2023). 30, 57-64 https://doi.org/10.1107/S1600577522011080
[4] Latent Bayesian optimization for the autonomous alignment of synchrotron beamlines
T. W. Morris, Y. Du, M. Fedurin, A. C. Giles, P. Moeller, B. Nash, M. Rakitin, B. Romasky, A. L. Walter, N.
Wilson, A. Wojdyla; Proceedings of SPIE 12697, Advances in Computational Methods for X-Ray Optics
VI; 126970B (2023) https://doi.org/10.1117/12.2677895
