Lubov Maxim, Goray Leonid
St Petersburg Academic University, Khlopin St 8/3 Let A, St Petersburg 194021, Russian Federation.
J Synchrotron Radiat. 2019 Sep 1;26(Pt 5):1539-1545. doi: 10.1107/S1600577519006337. Epub 2019 Jul 19.
A new design for a high-efficiency multilayer-coated blazed X-ray grating with horizontal-shifted (non-conformal) boundary profiles is proposed. The investigation of the grating design is carried out using an integrated approach based on rigorous numerical calculations of light diffraction by gratings with realistic boundary profiles obtained from simulations of multilayer grating growth. By varying the incidence angle of the deposition flux, one can set the direction and magnitude of the boundary profile shifts over a wide range of values. It is shown that the diffraction efficiency of the blazed gratings with shifted boundary profiles may be substantially higher than the efficiency of gratings with conformal boundaries, which are, moreover, much more difficult to produce. High-efficiency gratings with shifted boundaries can be obtained when the deposition is mainly on the blaze facet with a high inclination of the deposition flux, as opposed to widely used near-normal deposition methods. The maximum absolute efficiency of a W/B4C 2500 mm grating with a blaze angle of 1.76° and an anti-blaze angle of 20°, working at a blaze wavelength of 1.3 nm and having shifted realistic boundary profiles, obtained using our integrated approach is 23.3%, while that of a grating with the ideal (triangular) boundary profile and the same shifts is 25.3%, and that of an ideal conformal profile is only 22.2%. The maximum absolute efficiency of 40.2% of a 2500 mm Cr/C grating with a blaze angle of 1.05° and a realistic anti-blaze angle of 10°, working at a blaze wavelength of 0.83 nm and having ideal shifted boundaries, is higher than the maximum efficiency of the similar grating having ideal conformal boundaries with a non-realistic anti-blaze angle of 80°.
提出了一种具有水平偏移（非共形）边界轮廓的高效多层镀膜闪耀X射线光栅的新设计。基于对多层光栅生长模拟得到的具有实际边界轮廓的光栅光衍射的严格数值计算，采用综合方法对光栅设计进行了研究。通过改变沉积通量的入射角，可以在很宽的值范围内设置边界轮廓偏移的方向和大小。结果表明，具有偏移边界轮廓的闪耀光栅的衍射效率可能显著高于具有共形边界的光栅，而且后者的制造难度要大得多。与广泛使用的近垂直沉积方法相反，当沉积主要发生在具有高倾斜度沉积通量的闪耀面上时，可以获得具有偏移边界的高效光栅。使用我们的综合方法得到的W/B4C 2500 mm光栅，其闪耀角为1.76°，反闪耀角为20°，在闪耀波长1.3 nm下工作，具有实际偏移边界轮廓，其最大绝对效率为23.3%，而具有理想（三角形）边界轮廓且相同偏移的光栅的最大绝对效率为25.3%，理想共形轮廓的光栅的最大绝对效率仅为22.2%。2500 mm Cr/C光栅，闪耀角为1.05°，实际反闪耀角为10°，在闪耀波长0.83 nm下工作，具有理想偏移边界，其最大绝对效率为40.2%，高于具有理想共形边界且反闪耀角为80°（不实际）的类似光栅的最大效率。
