Recent advances in EUV multilayer optics for solar physics and ultra-fast science applications (Conference Presentation)

In the last decades, extreme ultraviolet (EUV) multilayer coatings have proved to be key components in the development and success of telescope imagers onboard space missions to image the solar corona. More recently, we have been able to significantly increase the efficiency, to develop new functionality and to extend the range of operation of EUV multilayer coatings, thanks to the development and optimization of new material combinations and new coating designs. Furthermore, multilayer mirrors with high efficiency, good stability, enhanced selectivity and/or broad bandwidth and phase controlled are key components to manipulate the ultra-short pulses generated by coherent sources. In this presentation, we will review the recent development of EUV multilayer optics for solar imaging, in particular for the two Solar Orbiter EUV telescopes, which produced the closest images of the Sun in 2022 with the first dual-band EUV coatings. We will also discuss multilayer mirrors for pico-, femto- and attosecond sources, including the recent development of a delay line with advanced multilayer optics for the femto/attosecond beamlines in Paris-Saclay (ATTOLAB). We will finally discuss the problem of inaccuracies in the available EUV optical properties of materials that makes it difficult to design and calibrate such instruments. We will discuss solutions to improve the accuracy in the determination of optical properties.