Visible light performance of x-ray filters for Einstein probe

To achieve accurate detection of different space x-ray sources, three types of filters are designed for the follow-up x-ray telescope onboard the Einstein probe (EP). Two of them are supported by PI mesh and Ni stiffener, which are studied in this paper. Since visible light blocking performance of these filters is important for x-ray detection, the transmittance and visible light irradiation damage performance of them are measured and presented. With a self-built double-beam laser system, the detection sensitivity of transmittance at 532 nm is increased to 10( - 9) compared with 10( - 5) for the spectrophotometer. Moreover, the tests of visible light irradiation damage performance under vacuum and air conditions have been carried out using this system, which proves that the filters have good reliability. Finally, the topography of these filters is studied and described with a microscope.