一种新型透射式自聚焦光栅的设计及理论研究

结合普通透射光栅的分光特性和菲涅耳波带片的聚焦特性，提出一种应用于软X射线波段的新型透射式自聚焦光栅。根据菲涅耳衍射理论，对其衍射特性进行理论推导，证明该新型光栅存在一个与光栅平面垂直的焦平面，不同波长的光波聚焦于该焦平面的不同位置。在焦平面上，焦点位置随光子能量的变化是线性的，即能实现光子能量的线性测量。通过解析推导，得到在沿着焦平面和垂直于焦平面两个方向上光斑的展宽模式,发现该新型光栅在沿着焦平面的光斑展宽模式不同于普通光栅。根据基尔霍夫衍射公式，设置实用化参数，对其衍射模式进行了详细的数值模拟研究，并讨论了相应的测谱范围和谱分辨率。

Design and theoretical studies of a novel transmission self-focusing grating

Combining the dispersion properties of traditional transmission grating and the focusing properties of Fresnel zone plate, we propose a novel transmission self-focusing grating used in soft X-ray region. According to Fresnel diffraction theory, the gratings diffraction properties are derived theoretically, proving that there is a focal plane perpendicular to the grating plane and light waves with different wavelengths focus on different positions of the focal plane. At the focal plane, the photon energy varies linearly with the focal position, which means its able to achieve linear measurement of photon energy. The broadening pattern of focal spot at and perpendicular to the focal plane are obtained by analytic derivation. According to Kirchhoff diffraction formula, a detailed numerical simulation of diffraction patterns is performed by setting practical parameters, and the corresponding measured spectral range and spectral resolution are discussed in detail.