龙虾眼透镜成像的三维矢量衍射影响研究

Lobster eye optical technology is a research focus in the field of Mimetic Optical Technology. Lobster eye lens can obtain unprecedented widely view field and energy collecting efficiency in the field of high energy space detection, because of its unique imaging principle and spatial structure. The high resolution is one of the preconditions to realize the deep space positioning detection, which requires the micro-channel structure of lobster eye lens is small enough to reduce the geometrical aberration. In recent years, with the rapid development of the Micro-Nano Machining Technique, that can fabricates the spherical micro-channel array with smooth internal surface in micron level, and that makes lobster eye lens have a high spatial resolution is possible. As the development of the micro-channel structure scale towards Micro-scale or Nano-scale dimension in lobster eye lens, the diffraction and vector characteristics of electromagnetic radiation will be even more remarkable. But the design of the lobster eye lens system still stay within geometrical optics at present and the lack of the physical optics imaging theory to severely restricted the high precision design of lobster eye lens system. Therefore, this project will study the influence of 3-D vector diffraction effect of the micro-channel structure in the lobster eye lens system from the perspective of physical optics. Through building up the 3-D vector diffraction mathematical model of the lobster lens micro-channel structure and diffraction propagation mathematical model of the micro-channel array, that relationship between the parameters of lobster eye lens, the structure parameter of micro-channel and the diffraction field distribution relationship could be obtained at image plane. The design limit of lobster eye lens is revealed and the theoretical foundation for high precision optimization design of the lobster lens system is established by constructing the evaluation function within physical optics mechanism.

龙虾眼透镜是仿生光学技术的一个研究热点。其独特的成像原理能够在空间高能射线探测领域获得前所未有的大视场与较高的能量获取能力。高精度的空间分辨是实现深空定位探测的前提，这要求龙虾眼透镜具有足够小的微通道结构，用以减小几何光学的像差。随着龙虾眼透镜的微通道结构尺度向着微纳米尺度方向发展，其电磁辐射的波动性与矢量特性将越发显著。但目前龙虾眼透镜系统的设计仍然停留在几何光学的范畴之内，物理光学成像理论研究的缺乏，严重制约了高精度龙虾眼成像系统的设计。所以本项目拟以物理光学视角，研究微通道结构的三维矢量衍射效果对于龙虾眼透镜成像机制的影响。通过建立龙虾眼透镜微通道结构的三维矢量衍射数学模型和微通道阵列的衍射场传播数学模型，得到龙虾眼透镜参数与微通道结构参数和像面处的衍射光场分布的关系。通过构建物理光学机制下的评价函数，揭示龙虾眼透镜的设计极限，为高精度龙虾眼透镜系统的成像优化设计奠定理论基础。

龙虾眼透镜系统具有能量利用率高，视场范围大，光谱色散效果小等特点，反射聚焦机理使得它可以应用于高能射线聚焦领域，应用范围包括：大视场实现空间高能射线的周天定位探测和小型化X射线探测设备。本项目以龙虾眼透镜成像过程中的物理与几何光学问题为研究对象，构建成像质量评价方法，奠定高精度龙虾眼透镜系统设计的理论基础。.本项目研究了龙虾眼透镜由于微通道结构尺寸所带来的衍射效应，使用严格矢量衍射分析手段对不同波长条件下的微通道结构进行了衍射分析。同时考虑了由于金属反射面所带来的通道传输吸收效应。基于龙虾眼透镜的多源探测应用需求，从软X射线谱段到可见光谱段进行了微通道衍射弥散斑分析，得到了预期的衍射限制，为长波谱段龙虾眼透镜的设计提供了依据。.通过建立子午平面内的多次反射等效模型，简化了光束在微通道内多次反射的传输过程，完整的描述了大视场、高反射率条件下龙虾眼透镜的像差分布；同时根据该数学模型完整的求解了龙虾眼透镜的各个参数与龙虾眼透镜集光效率之间的关系，发现了龙虾眼透镜最优效率结构定值。当忽略材料反射率随入射角的变化时，龙虾眼透镜的最优效率结构与视场角与通道的长径比直接相关，并且它们的乘积为定值。当龙虾眼透镜工作在X射线波段时，材料的反射率限制了龙虾眼透镜的有效视场，此时最优效率结构由通道长径比与有效视场共同决定。这些结论为高能龙虾眼透镜的设计工作带来了极大的便利。.针对实际加工过程中工艺方法所带来的差异，实现了不同通道截面的龙虾眼透镜轴上物点的点扩散函数的求解与仿真分析。通过对比分析发现方形通道龙虾眼透镜与子午型龙虾眼透镜的成像区别在于：1.方形通道龙虾眼透镜没有理想近轴像点；2.相比于子午型龙虾眼透镜，方形通道龙虾眼透镜具有更高的能量收集效率，但同时方形龙虾眼透镜的十字形杂散焦臂会更早出现。这些研究成果有助于提升龙虾透镜的光学设计水平。