第四代同步辐射光源为多个研究领域提供了亮度和相干度更高、性能更加优异的X射线。为了充分发挥这些光束的潜力,需要精确的光束线装调和高质量的X射线光学元件。波前检测技术在这些方面发挥着重要作用。近10年来快速发展起来的基于X射线近场散斑的波前检测技术,具有简便易行、测量精度高等优点。利用散斑在深菲涅耳区形状和大小不变的特性,在参考图和样品图之间进行互相关计算,提取出入射波、待测光学元件透射波或反射波的波前信息。综述了利用X射线近场散斑开展波前检测的研究现状,介绍了X射线散斑追迹技术、X射线散斑向量追迹技术、X射线散斑扫描技术、自相关X射线散斑扫描技术、通用调制图样分析技术和Ptychographic X射线散斑追迹技术的原理、实验流程,以及各自的优势和应用。

本文总结了当前同步辐射 X射线反射镜光学制造技术的需求背景、发展现状以及未来方向。同步辐射光源是国家重大科学装置, 作为同步辐射光源重要光学元件的 X射线反射镜, 直接决定着光学调制品质。短波长掠入射的特殊应用场景, 使 X射线反射镜有着更为特殊且高精度的面形要求, 其加工与检测技术长期为国外所垄断, 国内发展较为缓慢, 面对国内未来同步辐射装置的建设需求, 我国亟需打破这一现状。

利用激光速率方程理论，对Tm，Ho激光系统计算预测得出最佳耦合输出透过率和调Q激光脉冲宽度。实验采用Tm， Ho:LuLF为增益介质，三向侧面泵浦，环形腔声光调Q。选用透过率20%和30%的输出镜作对比。在透过率20%耦合输出时，得到调Q激光脉冲能量最大为58.0 mJ，对应光光转换效率为1.45%；在透过率30%耦合输出时，得到调Q激光脉冲能量最大为62.9 mJ，对应光光转换效率1.57%，并且获得了最大动静比48.7%。激光脉冲宽度在注入能量3.25 J时为417.2 ns。与理论计算结果较为一致。

In this letter, a new single three-dimensional (3D) laser projector is proposed. As liquid crystal (LC) can produce two image patterns with orthogonal polarization states at 120 Hz, only one projector is required in this approach for reconstruction of a 3D object. The light source is made up of RGB (red, green, and blue) lasers because laser has lots of advantages such as longer life, higher brightness, and larger color gamut. A novel diffusive media with good polarization-maintaining quality is used as rear projection screen for its high transmission efficiency (～90%) and low reflection efficiency. When laser incidents into the diffusive media, which contains lots of spherical particles with sizes between 2 and 15 \mu m, laser is scattered randomly and the laser speckle is reduced. A spatial phase mask is also inserted into the optical path to reduce speckle. With these techniques, the speckle contrast is reduced to 0.1 and the quality of image patterns has been greatly improved.

The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot. It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning. The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.