François THUILLIER will defend his thesis entitled “Photo-induced thermal radiation of optical thin films” on Friday, 13th of March, at 10:00 a.m. in Amphi Rouard, campus St Jerome, in Marseille. The presentation will be in French.
The jury is composed of :
– Nathalie DESTOUCHES, Professeure, Université Jean Monnet, St Etienne, President
– Franck ENGUEHARD, Professeur, PPrime Poitiers – Reviewer
– Philippe BOUCAUD, DR CNRS, CHREA Nice – Reviewer
– Olivier UTEZA, DR CNRS, LP3 Marseille – Examinator
– Karine MATHIEU, Responsable service optique, CNES – Examinator
– Laurent LAMAIGNERE, Directeur de recherche, CEA -Examinator
– Claude AMRA, DR CNRS, Institut Fresnel – Thesis Co-director
– Myriam ZERRAD, IGR AMU HDR, Institut Fresnel – Thesis Director
– Hélène KROL, Ingénieure de recherche, CILAS – Invited
– Paul ROUQUETTE, IR CNRS, Institut Fresnel – Invited
Abstract : Interference filters are used in all modern optical systems and cover a wide range of applications, from telecommunications to healthcare. Significant progress has been achieved in the fabrication and synthesis of these components. Sophisticated metrology tools have also been developed to investigate absorption, scattering, and laser-induced damage processes, as well as various non-optical properties of the components. In this high-precision context, the thermal radiation emitted by multilayer systems has been comparatively less studied, even though it can provide valuable information about the state of the component, its emissivity/absorption, and its temperature under continuous, pulsed, or modulated optical excitation. Knowing this temperature is essential for understanding thermally induced degradation phenomena under optical flux. Moreover, multilayer systems can be engineered to control thermal radiation or redirect it toward specific spectral bands, thereby opening the way to additional applications in security, defense, and energy. This doctoral work is first dedicated to the design and implementation of an optical system capable of measuring the thermal emission from broadband light absorbers (metal–dielectric structures) in response to nanosecond optical pulses. The performance of the instrument in the mid-infrared domain—particularly its dynamic range, accuracy, and detectivity threshold—is presented in detail. The thermal emission measurements are then used to reconstruct the temporal evolution of the temperature with a ns resolution, over the full duration of the thermal signal. Several methods are proposed for this purpose. It is shown that the agreement between calculations and measurements is very good, provided that the spatial distribution of temperature across the sample is properly taken into account.
Keywords : Thermal radiation, Optical thin films, Photo-induced radiation, Metrology, Temperature
