Diffraction efficiencies of holographic laminar and blazed types gratings for use in a flat-field spectrograph in the 50-200 eV range for transmission electron microscopes

Imazono, Takashi; Koike, Masato; Kawachi, Tetsuya; Koeda, Masaru*; Nagano, Tetsuya*; Sasai, Hiroyuki*; Oue, Yuki*; Yonezawa, Zeno*; Kuramoto, Satoshi*; Sano, Kazuo*

We have been developing a compact wavelength-dispersive soft X-ray spectrometer to be attached to electron microscopes, which places emphasis on the low energy region for the demanding analysis of the Li- emission spectrum in the development of lithium-ion batteries. For this purpose, a flat-field holographic spherical grating was designed employing aspheric wavefront recording system. Laminar and blazed master (LM and BM) gratings and their respective replica (LR and BR) gratings were fabricated by holographic exposure and ion-beam etching methods. Absolute diffraction efficiencies in an energy range of 50-200 eV were measured. The first order diffraction efficiencies of the LM gratings were 5-20% in the measured energy range and 6-9% at 54.3 eV. Those of the BM gratings strongly depended on the blaze angles and they were 5-27% and 11%, respectively. Both LR and BR showed the comparable efficiencies with their respective master gratings.