Two-color reflection multilayers for He-I and He-II resonance lines for microscopic ultraviolet photoelectron spectroscopy using Schwarzschild objective

Two-color multilayers reflecting both He-I (58.4 nm) and He-II (30.4 nm) resonance lines have been designed and fabricated as reflection coatings of mirrors of Schwarzschild objectives used for microscopic ultraviolet photoelectron spectrometers. The multilayer was designed to consist of a top single layer and piled double layers so that its normal incidence reflectances for both He-I and He-II resonance lines are more than 20%. Multilayers of SiC(top layer)-Mg/SiC(double layers) and SiC(top layer)-Y₂O₃/Mg (double layers) are fabricated, and their reflectances for the He-I and He-II lines are 25% and 20%, and 23% and 26%, respectively.