Fabrication and evaluation of a wide-band multilayer laminar-type holographic grating for use with a soft X-ray flat field spectrograph in the region of 1.7 keV
Imazono, Takashi; Ishino, Masahiko; Koike, Masato; Sasai, Hiroyuki*; Sano, Kazuo*
A multilayer laminar-type holographic grating having an average groove density of 2400 lines/mm is designed and fabricated for use with a soft X-ray flat field spectrograph covering the 1.7-keV region. A varied-line-spaced grooves pattern is generated by the use of an aspheric wavefront recording system and laminar-type grooves are formed by a reactive ion-etching method. Mo/SiO multilayers optimized for the emission lines of Hf-M, Si-K, and W-M are deposited on one of the three designated areas on the grating surface in tandem. The measured first-order diffraction efficiencies at the respective centers of the areas are 1820%. The flat field spectrograph equipped with the grating indicates a spectral line width of 814 eV for the soft X-ray emission spectra generated from electron-impact X-ray sources.