球面弯晶成像的优化设计及实验测试

Optimum design and test experiments of spherically bent crystal imaging

为满足"神光Ⅱ"升级激光装置实验的激光等离子体高空间分辨和窄带宽的精密成像诊断需求,本文研究球面弯晶单色成像技术,并对其进行优化设计及实验验证。首先,使用光线追迹方法分析了成像像距、布拉格角、背光源尺寸等成像系统参数对球面弯晶成像性能的影响,分析了设计参数的变化对成像空间分辨能力的影响,并在X射线管上开展了测试验证实验。研究结果表明:二维成像时,在等分辨成像像距处可以获得较好的成像结果,增大布拉格角可以抑制像差进而提高成像质量,更小的背光源尺寸也有助于提高成像的空间分辨率。测试实验获得了清晰的网格背光成像,成像结果与预期相符,空间分辨率优于14μm。这一工作有助于球面弯晶成像系统的优化设计及其在激光等离子体精密诊断中的应用。

In order to achieve high spatial resolution and narrow spectral bandwidth imaging of laser plasma in updated SGⅡlaser facility,the relations of the imaging quality of spherically bent crystal with image distance,Bragg angle and backlit size were discussed.First,spherically bent crystal imaging at diverse image distances,Bragg angles and backlit sizes were studied with a ray tracing program X-LAB.Then,a test experiment was carried out by using X ray tube device.The results show that better two dimension image could be obtained at the image distance of equal resolution of two dimensions,and larger the Bragg angle is,better the imaging is.Furthermore,smaller size of backlit is also helpful to improve the imaging quality.The experiment result agrees well with the expectation,a spatial resolution better than14μm in the image of the mesh.The results obtained contribute to the optimization design of the spherically bent crystal imaging system and precision diagnosis of laser plasma.