N,S co-doped carbon nanodots are prepared and utilized in a facile fluorescent cytosensor.

In this paper, the adaptive liquid (AL) lenses are introduced into the double-sided telecentric zoom system, which could greatly decrease the mechanical motion group compared with the traditional zoom system, and only one movable aperture stop (STO) is retained. Firstly, this paper derived the Gaussian brackets used in this system, and we found the appropriate screening method to get the suitable initial structure parameters from the solution space. Then we used the lens module design method to create the initial system. Finally, we used CODEV to further optimize the system, and we got an excellent design result, which controlled the telecentricity of both sides within 0.1°, the distortion was controlled within 0.5%, and the MTF of each zoom configuration above 0.3. This optical system has high application potential and value in the field of precision machine vision. The design method proposed in this article can effectively solve the problem that the zoom system using adaptive liquid lenses lacks the initial structure.

We present a large-range and high-precision autofocus method based on an annular diffractive optical element (DOE) for a laser direct writing system. By analyzing the shape of the return spot, the defocus direction and the defocus amount can be obtained at the same time. The experimental results show that the linear detection range of the proposed method can reach at least 76 µm, the sensitivity can reach 100 nm, the detection accuracy can reach 100 nm, and the noise fluctuation does not exceed 50 nm. Apparently, with the advantages of a large detection range, high detection, and good stability, the automatic focus detection method proposed in this paper can be widely applied in various wafer-scale complex microstructure preparation systems.

As a kind of information-intensive 3D representation, point cloud rapidly develops in immersive applications, which has also sparked new attention in point cloud compression. The most popular dynamic methods ignore the characteristics of point clouds and use an exhaustive neighborhood search, which seriously impacts the encoder’s runtime. Therefore, we propose an improved compression means for dynamic point cloud based on curvature estimation and hierarchical strategy to meet the demands in real-world scenarios. This method includes initial segmentation derived from the similarity between normals, curvature-based hierarchical refining process for iterating, and image generation and video compression technology based on de-redundancy without performance loss. The curvature-based hierarchical refining module divides the voxel point cloud into high-curvature points and low-curvature points and optimizes the initial clusters hierarchically. The experimental results show that our method achieved improved compression performance and faster runtime than traditional video-based dynamic point cloud compression.

Defocus detection technology is the key technology in the fields of laser direct writing, optical disc storage, and high-precision lithography, which directly affects the accuracy of line drawing. In this paper, using the principle of astigmatic method, combined with differential technology, a nano-level defocus detection method based on differential astigmatism for the high numerical aperture systems is proposed. Firstly, by establishing a mathematical model, the theoretical analysis and simulation of the defocus detection method based on differential astigmatism are carried out. In addition, the system parameters at the maximum sensitivity of the high numerical aperture defocus detection system is also solved. Secondly, the defocus detection experimental system based on astigmatic method was built for experimental demonstration. Finally, using the objective lens with a numerical aperture of 0.8, the focus error signal curve with a good linear relationship is obtained in this paper. The linear range is 6μm; the system sensitivity can reach 5 nm; the system detection accuracy is 30 nm, and the repeat positioning accuracy can reach 30 nm. The defocus detection method based on the high numerical aperture objective lens has the advantages of large detection range, high detection accuracy and compact system structure, which can be widely used in various new high-precision laser processing fields.