– Aude LEREU – Institut Fresnel, CNRS, President of the jury
– Patricia SEGONDS – Institut Néel, Université Grenoble Alpes, Reviewer
– Jean-François ROUSSEL – Département de Physique ONERA, Toulouse, Reviewer
– Laurent LAMAIGNÈRE – Département Lasers de puissance CEA Cesta, Examiner
– Julien NILLON – Amplitude Laser, Pessac, Invited member
– Laurent GALLAIS – Institut Fresnel, Centrale Méditerranée, Thesis Director
– Frank WAGNER – Institut Fresnel, Aix-Marseille Université, Co-director
Abstract : Over the past decades, pulsed laser sources have seen significant increases in power, repetition rate, and operational lifetime. In the sub-picosecond UV range, this evolution raises growing concerns about the reliability of optical components, which are exposed to laser-induced contamination: the formation of surface deposits that can degrade transmission, wavefront quality, and beam performance. This thesis focuses on the experimental analysis and modeling of this phenomenon at 343 nm, as well as its impact on beam propagation. A dedicated experimental setup was developed to reproduce and characterize deposit growth. A phenomenological growth model was then proposed, followed by a numerical propagation model linking deposit topography to the observed degradations. Finally, an original in situ measurement method was developed to try to monitor contamination evolution.
This work provides new insights into laser-induced contamination in the sub-picosecond UV regime and opens perspectives for in situ monitoring, environmental control, and mitigation strategies.
