Caption: Picture of one of the five thermal filters designed by UNIPA/INAF-OAPA to protect the X-IFU TES array from IR radiative load. The filter, named THF2, has a 56 mm clear aperture diameter and consists of a thin polyimide film 45 nm thick coated with 30 nm of aluminium attached to a fine mesh of Au-plated BeCu alloy. The mesh, which has a 2% geometrical blocking factor, provides mechanical support to the thin membrane and Radio Frequency attenuation below 6 GHz. This breadboard will undergo a series of optical and environmental characterisation tests within the first two months of 2023 to demonstrate the Technology Readiness Level 5/6.

Credit: Luxel Corporation.