Design of soft x-ray laminar-type gratings coated with supermirror-type multilayer to enhance diffraction efficiency in a region of 2-4 keV

Soft x-ray diffraction gratings coated with a supermirror-type multilayer were designed to enhance diffraction efficiency in the energy range of 2-4 keV by means of numerical calculations. The optimized groove depth and incidence angle are 2.05 nm and 88.65 degrees respectively, for the grating having a groove density of 3200 grooves/mm. Regarding the multilayer structure, the optimum number of B4C/W layers pair was 11 and the thickness of B4C was increased from bottom to top, while that of W was kept constant. The replacement of the top layer of W by either Co, Cr, or Ni was an effective means of obtaining uniform diffraction efficiency. In the region of 2-4 keV, the calculated diffraction efficiency of the designed gratings was up to similar to 5.3%, on average, and almost eight times larger than that of similar to 0.7% of an Au coated grating.

Automated summary

Soft x-ray diffraction gratings coated with a supermirror-type multilayer were numerically optimized to enhance diffraction efficiency in the energy range of 2-4 keV. The optimized groove depth and incidence angle were determined to be 2.05 nm and 88.65 degrees, respectively, for a grating with a groove density of 3200 grooves/mm. The replacement of the top layer of W with Co, Cr, or Ni effectively improved the uniformity of diffraction efficiency, resulting in calculated diffraction efficiency of up to approximately 5.3% in the 2-4 keV range, almost eight times larger than that of an Au coated grating (approximately 0.7%).