Development of the multi-layer high-reflectivity polarizing mirror for the magnetic field measurement of the solar atmosphere in Lyman-alpha line

研制了用于Lyman-alpha线（121.6 nm）太阳大气磁场测量的多层高反射率偏振镜。该镜面由熔融二氧化硅衬底上的MgF2和SiO2层组成。我制作了这种镜子的测试片，并在同步加速器设备上测量了它们的性能。Lyman-alpha线s-偏振光和p-偏振光的反射率分别为Rs = 54.8%和Rp = 0.29%。因此，极化功率P = (Rs-Rp)/(Rs+Rp)为0.99。这意味着这面镜子几乎只反射s偏振光。这种反射镜的Rs比常用的MgF2板大2.5倍，其Rs为22%。在此基础上，得出高反射率偏振镜研制成功的结论。

I developed the multi-layer high-reflectivity polarizing mirror for the magnetic field measurement of the solar atmosphere in Lyman-alpha line (121.6 nm). This mirror consists of MgF2 and SiO2 layers on a Fused Silica substrate. I fabricated the test pieces of this type mirror, and measured their performance at the Synchrotron facility. The measured reflectivities for s- and p- polarized lights in Lyman-alpha line are Rs = 54.8% and Rp = 0.29%, respectively. Hence, the polarizing power P = (Rs-Rp)/(Rs+Rp) is 0.99. This means that this mirror reflect almost only s-polarized light. The Rs of this mirror is about 2.5 times larger than the MgF2 plate that is commonly used and whose Rs is 22%. On the basis of these results, it is concluded that the high-reflectivity polarizing mirror has been successfully developed.