The compact, sensitive, and multidimensional displacement measurement device plays a crucial role in semiconductor manufacture and high-resolution optical imaging. The metasurface offers a promising solution to develop high-precision displacement metrology. In this work, we proposed and experimentally demonstrated a two-dimensional displacement (XZ) measurement device by a dielectric metasurface. Both transversal and longitudinal displacements of the metasurface can be obtained by the analysis of the interference optical intensity that is generated by the deflected light beams while the metasurface is under linearly polarized incidence. We experimentally demonstrated that displacements down to 5.4 nm along the x-axis and 0.12 µm along the z-axis can be resolved with a 900 µm × 900 µm metasurface. Our work opens up new possibilities to develop a compact high-precision multidimensional displacement sensor.

光固化3D打印是制造高度复杂结构陶瓷的一种有效方法。打印的样件需要经历脱脂和烧结等热处理才能成为可用的陶瓷件, 脱脂工艺对打印件性能影响巨大。本工作通过研究脱脂工艺对DLP光固化3D打印制备的堇青石陶瓷性能的影响规律, 建立缺陷抑制策略。比较并分析了脱脂气氛和升温速率对陶瓷样件的表面裂纹和元素分布状态的影响, 还对比进一步烧结后样件显微组织、尺寸收缩率、相对密度和弯曲强度等性能。研究发现脱脂气氛对样件各性能影响最大, 使用氩气脱脂可显著降低表面裂纹, 提高相对密度与弯曲强度; 并确定最佳升温速率为1 ℃/min。最终获得表面完整无裂纹且相对密度为(94.6±0.3)%, 弯曲强度为(94.3±3.2) MPa的堇青石陶瓷样件。本研究为光固化3D打印堇青石陶瓷的无缺陷制造与应用提供了科学依据与技术参考。

陶瓷以其优异的热物理化学性能在航空航天、能源、环保以及生物医疗等领域具有极大的应用潜力。随着这些领域相关技术的快速发展, 其核心零件部件外形结构设计日益复杂、内部组织逐步走向定制化、梯度化。陶瓷具有硬度高、脆性大等特点, 较难通过传统的加工成形方法实现异形结构零件的制造, 最终限制了陶瓷材料的工程应用范围。激光增材制造技术作为一种快速发展的增材制造技术, 在复杂精密陶瓷零部件的制造中具有显著优势: 无模、精度高、响应快以及周期短, 同时能够实现陶瓷零件组织结构灵活调配, 有望解决上述异形结构陶瓷零件成形问题。本文综述了多种基于粉末成形的激光增材制造陶瓷技术: 基于粉末床熔融的激光选区烧结和激光选区熔化; 基于定向能量沉积的激光近净成形技术。主要讨论了各类激光增材陶瓷技术的成形原理与特点, 综述了激光选区烧结技术中陶瓷坯体后处理致密化工艺以及激光选区熔化和激光近净成形技术这两种技术中所打印陶瓷坯体基体裂纹开裂行为分析及其控制方法的研究进展, 对比分析了激光选区烧结、激光选区熔化以及激光近净成形技术在成形陶瓷零件的技术特征, 最后展望了激光增材制造陶瓷技术的未来发展趋势。

Phase carried by two orthogonal polarizations can be manipulated independently by controlling both the geometric size and orientation of the dielectric nanopost. With this characteristic, we demonstrate a novel multifunctional metasurface, which converts part of the incident linearly polarized light into its cross-polarization and encodes the phase of the two orthogonal polarizations independently. A beam splitter and a bifocal metalens were realized in a single-layer dielectric metasurface by this approach. We fabricated the bifocal metalens and demonstrated that two focal spots in orthogonal polarizations can be separated transversely or longitudinally at will. The proposed approach shows a new route to design multifunctional metasurfaces with various applications in holography and three-dimensional display.