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The non-contact three-dimensional measurement and reconstruction techniques have played a significant role in the packaging and transportation of precious cultural relics. This paper develops a structured light based three-dimensional measurement system, with a low-cost for cultural relics packaging. The structured light based system performs rapid measurements and generates 3D point cloud data, which is then denoised, registered and merged to achieve accurate 3D reconstruction for cultural relics. The multi-frequency heterodyne method and the method in this paper are compared. It is shown that the relative accuracy of the proposed low-cost system can reach a level of 1/1000. The high efficiency of the system is demonstrated through experimental results. [ABSTRACT FROM AUTHOR]

Triangular single-crystalline nanorings of PbS were prepared at the air/water interface and characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV−vis spectroscopy. The nanorings were transformed from triangular PbS nanopyramids that were formed under Langmuir monolayers of arachidic acid (AA) through interfacial reactions between Pb2+ions in the subphases and H2S in the gaseous phase. The basal plane of the pyramids is a (111) face of PbS crystals with rock salt crystal structure, which is parallel to the air/water interface. The tips of the pyramids beneath the interface dissolved gradually due to selective etching of Pb2+in the nanocrystals by Cl−ions in the subphase because of their higher surface energy, resulting in the formation of the rings. The size of the rings could be tuned by changing the experimental conditions, and the optical properties changed when the rings formed. [ABSTRACT FROM AUTHOR]