Liu Yijie, Li Xuexuan, Jiang Pengfei, Wang Ziyue, Guo Jichang, Luo Chao, Wei Yaozhong, Chen Zhiliang, Liu Chang, Ren Wang, Zhang Wei, Qu Juntian, Zhang Zhen
Coal Mining Research Institute, China Coal Technology and Engineering Group Co., Ltd., Beijing 100013, China.
CCTEG Intelligent Strata Control Technology (Tianjin) Co., Ltd., Tianjin 300392, China.
Micromachines (Basel). 2024 Oct 11;15(10):1250. doi: 10.3390/mi15101250.
Micro-stereolithography (μSL) is an advanced additive manufacturing technique that enables the fabrication of highly precise microstructures with fine feature resolution. One of the primary challenges in μSL is achieving and maintaining precise focus throughout the fabrication process. For the successful application of μSL, it is essential to maintain the sample surface within a focal depth of several microns. Despite the growing interest in auto-focus devices, limited attention has been directed towards auto-focus systems in image-based auto-focus microscope systems for precision μSL. To address this challenge, we propose an image-based auto-focus microscope system incorporating visual servo control. In the optical design, a transflective beam splitter is employed, allowing the laser beam to pass through for fabrication while reflecting the focused beam on the sample surface to the microscope and camera. Utilizing captured spot images and the Foucault knife-edge test, a deep learning-based laser spot image processing algorithm is developed to determine the focus position based on spot size and the number of spot pixels on both sides. Experimental results demonstrate that the proposed auto-focus system effectively determines the relative position of the focal point using the laser spot image and achieves auto-focusing through visual servo control.
微立体光刻（μSL）是一种先进的增材制造技术，能够制造具有精细特征分辨率的高精度微结构。μSL的主要挑战之一是在整个制造过程中实现并保持精确聚焦。对于μSL的成功应用而言，将样品表面保持在几微米的焦深范围内至关重要。尽管对自动聚焦设备的兴趣日益浓厚，但针对基于图像的自动聚焦显微镜系统中用于精密μSL的自动聚焦系统的关注却有限。为应对这一挑战，我们提出了一种结合视觉伺服控制的基于图像的自动聚焦显微镜系统。在光学设计中，采用了半透半反分束器，使激光束能够穿过以进行制造，同时将样品表面上的聚焦光束反射到显微镜和相机上。利用捕获的光斑图像和傅科刀口测试，开发了一种基于深度学习的激光光斑图像处理算法，以根据光斑大小和两侧光斑像素数量确定聚焦位置。实验结果表明，所提出的自动聚焦系统利用激光光斑图像有效地确定了焦点的相对位置，并通过视觉伺服控制实现了自动聚焦。
