Liu Jian, Liu Jing, Liu Chenguang, Wang Yuhang
Opt Lett. 2020 Feb 1;45(3):660-663. doi: 10.1364/OL.384487.
The three-dimensional (3D) precision measurement of subsurface defects (SSDs) remains a long-term, critical, and urgent challenge in advanced manufacturing technology. In this study, we present a 3D dark-field confocal microscopy technique with complementary illumination and detection apertures to detect the SSD in ultraprecise optical components, which are widely employed at laser fusion facilities. Under an annular illumination generated using a pair of axicons, the specular reflected beam from the surface can be blocked by a diaphragm placed in the detection path, while the scattered beam from the SSD can be effectively collected by the detector. Both surface topography and subsurface defects distribution can be measured simultaneously by this method. We constructed a dark-field confocal microscope that could readily detect the SSD 60 µm beneath the surface in neodymium glass. Furthermore, the 3D volume distributions of the SSD were also reconstructed.
亚表面缺陷（SSDs）的三维（3D）精确测量在先进制造技术中仍然是一项长期、关键且紧迫的挑战。在本研究中，我们提出了一种具有互补照明和检测孔径的3D暗场共聚焦显微镜技术，用于检测超精密光学元件中的亚表面缺陷，这些元件广泛应用于激光聚变设施。在使用一对轴锥镜产生的环形照明下，表面的镜面反射光束可被放置在检测路径中的光阑阻挡，而来自亚表面缺陷的散射光束可被探测器有效收集。通过这种方法可以同时测量表面形貌和亚表面缺陷分布。我们构建了一台暗场共聚焦显微镜，它能够轻松检测钕玻璃中表面以下60微米处的亚表面缺陷。此外，还重建了亚表面缺陷的三维体积分布。
