An Online Dynamic Amplitude-Correcting Gradient Estimation Technique to Align X-ray Focusing Optics
Abstract
High-brightness X-ray pulses, as generated at synchrotrons and X-ray free electron lasers (XFEL), are used in a variety of scientific experiments. Many experimental testbeds require optical equipment, e.g Compound Refractive Lenses (CRLs), to be precisely aligned and focused. The lateral alignment of CRLs to a beamline requires precise positioning along four axes: two translational, and the two rotational. At a synchrotron, alignment is often accomplished manually. However, XFEL beamlines present a beam brightness that fluctuates in time, making manual alignment a time-consuming endeavor. Automation using classic stochastic methods often fail, given the errant gradient estimates. We present an online correction based on the combination of a generalized finite difference stencil and a time-dependent sampling pattern. Error expectation is analyzed, and efficacy is demonstrated. We provide a proof of concept by laterally aligning optics on a simulated XFEL beamline.
Cite
@article{arxiv.2208.11250,
title = {An Online Dynamic Amplitude-Correcting Gradient Estimation Technique to Align X-ray Focusing Optics},
author = {Sean Breckling and Leora E. Dresselhaus-Marais and Eric Machorro and Michael C. Brennan and Jordan Pillow and Malena Espanol and Bernard Kozioziemski and Ryan Coffee and Sunam Kim and Sangsoo Kim and Daewoong Nam and Arnulfo Gonzales and Margaret Lund and Jesse Adams and Daniel Champion and Ajanae Williams and Kevin Joyce and Marylesa Howard},
journal= {arXiv preprint arXiv:2208.11250},
year = {2022}
}