针对芯片实验室对浓度梯度产生器（CGG）的需求, 为制作侧壁垂直的CGG, 提出了一种移动焦平面正反面曝光制备SU-8光刻胶微结构的方法。该方法根据焦深将SU-8厚度分成多层, 每曝光一次焦面向下移动一层, 当曝光层数达到总层数一半时将样品翻转, 同样采用移动焦面重复曝光的方式使SU-8内部形成光化学反应通道, 得到充分曝光。最终利用SU-8微结构制作出聚二甲基硅氧烷 (PDMS) CGG。测试结果表明：SU-8微结构实际轮廓侧壁垂直, 没有出现 “T” 形结构, 沟道高度为49.4 μm；PDMS CGG侧壁垂直, 沟道深度为49.3 μm, 满足CGG侧壁垂直要求。

Overview: Two-photon lithography (TPL) has been a research hotspot in 3D micro/nano writing technology due to its characteristics of high resolution, low thermal influence, a wide range of processed materials, low environmental requirements, and 3D processing capability. It has shown unique advantages in the fields of life science, material engineering, micro/nano optics, microfluidic, micro machinery, and so on. This paper summarizes the research works done by researchers on different writing methods to improve TPL processing efficiency. Single-beam writing is the main method for TPL, which mainly depends on the speed of the scanning device. Single-beam writing has the advantages of simple system and high-quality beam, and it is easy to combine various effects to improve writing results. It mainly includes scanning modes based on the translation stage, galvo, polygon laser scanner, and acousto-optic deflector (AOD) (Fig. 2). All these modes have advantages and disadvantages. As for the scanning speed comparison, polygon laser scanner and AOD have relatively faster writing rates (faster than m/s). Multi-foci parallel lithography can obviously promote efficiency, elevating the speed by dozens or even hundreds of thousands of times, mainly based on spatial light modulator (SLM), digital micromirror device (DMD), microlens array (MLA), diffractive optical elements (DOE), multi-beam interference, and so on (Figs. 3-15). Multi-foci parallel lithography based on SLM is most widely used owing to its high efficiency and ability to flexible and independent control of each single beam, but the refresh rate is still insufficient. DMD has a higher refreshing rate (32 kHz), but the state-of-the-art beam parallelism realized by DMD is severely limited. More parallel beams are further required for improving the processing efficiency. The 2D pattern exposure method based on SLM or DMD can further improve the TPL efficiency with the superiority of generating flexibly designed pattern (Figs. 16-18). However, the 2D projection exposure technology is still difficult to achieve high writing precision, especially the axial resolution. An available method to improve the axial precision is spatially and temporally focusing an ultrafast laser to implement a strong intensity gradient at the spatial focal plane that restricts polymerization within a thin layer. The 3D projection method will be the most efficient writing method in the future, especially in 3D device processing (Figs. 19-20). Researchers used this technique to make hollow tubular and conical helices structures, increasing the processing speed by 600 times. However, the research results show that the current 3D projection can only process simple 3D structures. Further researches on 3D exposure processing of complex structures are expected, which will effectively expand its application in various fields. Authors believe that with the effort of researchers on efficiency improvement gradually, TPL can further highlight its advantages to promote the development of life science, materials engineering, micro-nano optics, and many other fields.

主要研究面曝光选区激光熔化单层成形时，激光光斑搭接率和电流对形状精度的影响。实验通过控制变量法研究搭接率、曝光时间、电流等工艺参数对激光光斑、熔道、圆环、尖角等成形形状精度的影响。实验结果表明：一定范围内，电流越大，激光光斑更均匀，成形一致性更好；搭接率38.4%能够获得最低的形状误差的熔道；搭接率一定，圆环成形误差随电流的增加而增加；尖角成形误差随着电流增加，呈现先增后减的趋势；搭接率为46.1%、38.4%时，零级衍射带来的形状误差降低。

与点扫描方式相比，面曝光选区激光熔化因具有成形效率高、残余应力水平低等优势，而成为极具发展前景的新一代选区激光熔化增材制造技术的发展方向。利用波长为915 nm的二极管连续激光器作为光源，结合电寻址反射式纯相位液晶空间光调制器，搭建了新一代面曝光选区激光熔化增材制造原理装置平台。获得了“○”形样式的面光斑曝光，基于光敏纸和低熔点金属粉末材料进行面曝光熔化成形并获得了样品，实现了面曝光选区激光熔化的原理性实验验证。