Study on optical blocking filter with Mg seed layer for soft X-ray space detection

In the field of X-ray space detection, the optical blocking filter which can transmit X-ray and block UV, visible and infrared light is required. The combination of polyimide film and Al coating is the most commonly used design of OBF. The Al island structure created during magnetron sputtering deposition affects the optical properties of OBF. In this work, the potential of Mg as a seed layer to improve the optical performance of OBF was investigated. Polyimide films coated with Mg-Al bilayer with different thickness parameters (the total thickness was the same, equaled to 80 nm) were prepared, and the effect of Mg on the optical properties of optical blocking filters was analyzed. The results show that the island structure of the Al coating is weakened by the addition of Mg seed layer. For optical blocking filter with 10 nm and 20 nm Mg seed layer, the UV, visible and infrared transmittance decreased significantly, and the X-ray transmittance increased slightly. The blocking performance of UV, visible and infrared light has no change with the variation of storage time.