Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

Mg-based multilayers, including SiC/Mg, Co/Mg, [B.sub.4]C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of [B.sub.4]C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4nm wavelength. OCIS codes: 310.1620, 230.4170, 040.7480, 340.6720, 350.6090.