软X射线掠入射金属光栅闪耀特性的 校正傅里叶展开微分法分析

在有限电导率光栅的微分理论中引入校正傅里叶展开方法,改善了计算收敛性。运用改进后的微分理论对软X射线波段掠入射金属光栅的闪耀特性做了数值分析,通过详细考察三角槽形、正弦槽形和矩形镀金光栅的软X射线-1级衍射效率对光栅结构参数和入射光状态参数的响应程度,给出了一种在使用和制作工艺上都能够接受的光栅技术指标。结果表明,作为闪耀波长为10.33 nm的软X射线波段掠入射镀金光栅,采用81°入射的刻线密度为1 200 l/mm,倾斜角为2°,顶角大于120°的三角槽形光栅较为合适,其效率可达到50%以上。同时,得到了一些优化软X射线波段掠入射金属光栅设计的新结论。

Analysis on blaze characteristics of grazing incidence metal grating in soft X-ray region by differential theory with correct Fourier expansion

In order to improve the convergence rate,a correct Fourier expand method was introduced to differential theory of the finite conductivity diffraction grating. Using modified differential theory of the finite conductivity diffraction grating, the diffraction characteristics of metal grating under grazing incidence in soft X-ray region were analysed numerically. After researching on effect of the efficiencies of the triangular, sinusoidal and rectangular gold lamellar gratings on the parameters of grating structure and incidence in soft X-ray region and -1 diffractive order, a acceptable grating technical specification was given out. Experimental result shows that for the grazing incidence gold grating in 1 200 groove/mm in soft X-ray region at blaze wavelength 10.33 nm, triangular grating efficiency can reach more than 50% when incidence is 81°, tilt angle is 2°, and apex angle is 120°. Meanwhile, some new conclusions in favor of designs on metal grating under grazing incidence in soft X-ray region were obtained.