Laminar and blazed type holographic gratings for a versatile soft X-ray spectrograph attached to an electron microscope and their evaluation in the 50-200 eV range

Imazono, Takashi; Koike, Masato; Kawachi, Tetsuya; Hasegawa, Noboru; Koeda, Masaru*; Nagano, Tetsuya*; Sasai, Hiroyuki*; Oue, Yuki*; Yonezawa, Zeno*; Kuramoto, Satoshi*; Terauchi, Masami*; Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Sano, Kazuo*

Laminar and blazed types holographic varied-line-spacing spherical gratings for use in a versatile soft X-ray flat-field spectrograph attached to an electron microscope are designed, fabricated, and evaluated. The absolute diffraction efficiencies of laminar (or blazed) master and replica gratings at 86.00 incidence evaluated by synchrotron radiation show over 5% (or 8%) in the 50-200 eV range with the maxima of 22% (or 26-27%). Also the resolving power evaluated by a laser produced plasma source is in excess of 700 at the energy near the emission spectrum of lithium (55 eV) for all gratings. Moreover, the emission spectrum of metallic Li with high spectral resolution is successfully observed with the spectrograph attached to a transmission electron microscope.