Nano Active Stabilization of samples for tomography experiments: A mechatronic design approach

Abstract

The fourth generation synchrotron light sources has yielded X-ray beams with a 100-fold increase in brightness and sub-micron focusing capabilities, offering unprecedented scientific opportunities while requiring end-stations with enhanced sample positioning accuracy.
At the European Synchrotron (ESRF), the ID31 beamline features an end-station for positioning samples along complex trajectories.
However, its micrometer-range accuracy, limited by thermal drifts and mechanical vibrations, prevents maintaining the point of interest on the focused beam during experiments.

To address this limitation, this thesis aims to develop a system for actively stabilizing the sample's position down to the nanometer range while the end-station moves the sample through the beam.
The developed system integrates an external metrology for sample position measurement, an active stabilization stage mounted between the end-station and the sample, and a dedicated control architecture.
The design of this system presented key challenges, first of which involved the design process.
To effectively predict how this complex mechatronic system would perform, a series of dynamical models with increasing accuracy were employed.
These models allowed simulation of the system's behavior at different design stages, identifying potential weaknesses early on before physical construction, ultimately leading to a design that fully satisfies the requirements.
The second challenge stems from control requirements, specifically the need to stabilize samples with masses from 1 to 50 kg, which required the development of specialized robust control architectures.
Finally, the developed Nano Active Stabilization System underwent thorough experimental validation on the ID31 beamline, validating both its performance and the underlying concept.

About This Repository & Reproducible Research

The foundation of this PhD thesis is built upon the principles of **reproducible research**.
Reproducible research is the practice of ensuring that the results of a study can be independently verified by others using the original data, code, and documentation.

This approach was adopted to increase transparency and trust in the presented research findings.
Furthermore, it is anticipated that the methods and data shared will facilitate knowledge transfer and reuse within the scientific community, thereby reducing research redundancy and increasing overall efficiency.
It is hoped that some aspects of this work may be reused by the synchrotron community.

The fundamental objective has been to ensure that anyone should be capable of reproducing precisely the same results and figures as presented in this manuscript.
To achieve this goal of reproducibility, comprehensive sharing of all elements has been implemented.
This includes the mathematical models developed, raw experimental data collected, and scripts used to generate the figures.

For those wishing to engage with the reproducible aspects of this work, all data and code are freely accessible in this Git repository.
The organization of the code mirrors that of the manuscript, with corresponding chapters and sections.
All materials have been made available under the MIT License, permitting free reuse.

This repository includes:

• Raw and/or processed data used in the analyses.
• MATLAB scripts and functions for data processing, simulations, and figure generation.
• Simulink/Simscape models developed or used during the research.
• A digital copy of the final PhD thesis document.