Study on Vibration and Acoustic Protection of Indium EUV Filters for Space Payloads

Extreme ultraviolet (EUV) thin-film filters are key optical components in space-based EUV imaging, employed to reject out-of-band visible and ultraviolet radiation. Currently, aluminum (Al) and zirconium (Zr) EUV filters are predominantly used due to their superior mechanical strength and stability. In contrast, indium (In) EUV filters had not been successfully deployed in spaceborne EUV cameras prior to this work. Their inherent fragility makes them highly susceptible to vibration and acoustic loads during the launch phase, ultimately resulting in structural failure. This study presents a comprehensive investigation into the structural protection strategies for indium EUV filters in space applications. Through systematic analysis of the photoenergy requirements and the mechanical characteristics of the indium filters, a robust filter assembly was developed, and vibration isolation as well as acoustic mitigation designs were implemented for the assembly. Finite element simulations and environmental tests confirmed that the indium filters can withstand vibration and acoustic loads. This technology has been successfully implemented in the 83.4 nm channel of the Extreme Ultraviolet Camera (EUVC) onboard the Queqiao-2 relay satellite for the Chang'E-7 mission. Subsequent in-orbit tests validated the structural integrity of the indium filters, providing a valuable technical reference for their successful application in future spaceborne EUV cameras.