Offer :
“Optimization of surface chemistry processes for hyper-polished mirrors“
Location : Institut Charles Gerhardt Montpellier
Dead line : june 30 2022
Thesis start date : september-october 2022
Context
Today, the preparation of the next generation of physics and astrophysics instrumentation requires to address technical challenges in optical fabrication, especially in term of surface figure errors. While the surface figure error of X-ray mirrors must be minimized to achieve a higher level of energy concentration at the beam lines output of synchrotrons, future Exo-Earth imaging space missions will require extremely precise optics to minimize speckles and achieve a 109 star/planet contrast. To address this challenge the LAM and Winlight Systems have established a partnership in the framework of a ANR Labcom program, and they collaborate with the Institut Charles Gerhardt. If current polishing techniques can allow to manufacture optical complex surfaces (aspherics) with less than 2nm Root Mean Square (RMS) figure errors, they still need to be improved. To achieve the previously mentioned scientific objectives, one must be able to manufacture mirrors in the 1.0m size range, with surface error lower than 1nm Peak-to-Valley corresponding to a few atomic layers, and a micro-roughness of the order of 1 Å RMS. To reach this level of accuracy, “non-contact” polishing techniques seem the most appropriate. Within this kind of process, one of the key elements to be studied, in close collaboration with the Institut Charles Gerhardt in Montpellier, is the slurry composition and characteristics, and its interaction with the mirrors surface. Optimized colloidal solutions of various oxide (SiO2, Al2O3, CeO2, ZrO2, …) nanoparticles will have to be synthesized and fully characterized within ICGM, and implemented in polishing processes at Winlight and LAM. The work will consist in optimizing the slurries for silicon but also for glasses that are used for astrophysics (Silica, Zerodur): minimizing sub-surface damage, optimizing Material Removal Rate (MRR), optimizing micro-roughness. The parameters to be optimized are the size, the chemical composition and the surface state of the nanoparticles, the additives of the slurry (salts, surfactants) and its pH and viscosity. The implementation of the slurries in polishing processes will be done at LAM and Winlight within already existing polishing workshops. Results about the obtained surface quality parameters will be analysed within the metrology labs of LAM, ICGM and Winlight (electronic microscope, AFM, X-ray diffraction, XPS, …).
Application
Duration: 36 months from September-October 2022.
Required skills: Sol-Gel, hydrothermal synthesis, surface chemistry, characterization of nanoparticles, optical characterization of surfaces, roughness measurement
Required profile: The candidate must have a Master M2 or engineering school diplomas in materials chemistry.
Host structure: The work will take place at the Charles Gerhardt Institute in Montpellier in the Chemistry and Molecular Materials Department (D1) with short travels/stays at LAM and Winlight premises in Marseille and Pertuis
Candidacy: The application must be made via the CNRS job portal at https://emploi.cnrs.fr/Offres/Doctorant/UMR7326-ANAMEK-032/Default.aspx
Contact: Dr. Yannick Guari (yannick.guari@umontpellier.fr). Mobile: 07 78 44 69 03.
Dr. Marc Ferrari (marc.ferrari@lam.fr)