Peng Xing, Kong Lingbao, Sun Xiang
Appl Opt. 2022 Mar 10;61(8):2108-2117. doi: 10.1364/AO.449810.
Light-emitting diodes (LEDs) have been widely utilized in machine vision lighting systems such as the process monitoring system in the additive manufacturing field, owing to their long life, high illumination efficiency, and controllable dimming. The quality of the lighting system directly affects the efficiency and accuracy of the entire monitoring system. However, existing designs cannot meet the optical efficiency and uniformity requirements at short lighting distances and small inspection areas with mixed multi-spectrum channels. This paper thus proposes a novel, to the best of our knowledge, design method of integrating a freeform surface lens and a square-shaped rod lens. The optical characteristics under different working distances and targeting surface types have been optimized and evaluated. Meanwhile, tolerance analysis has been utilized to demonstrate the feasibility of installation. With the use of the software Tracepro, simulation results showed that the designed composite machine vision lighting system can obtain an optical efficiency of 81.704% and an illuminance uniformity of 95.804% within the inspection area at a distance of 250 mm. Furthermore, verification experiments with a prototype were performed, demonstrating the feasibility of the proposed machine vision lighting system.
发光二极管（LED）因其寿命长、照明效率高和调光可控等优点，已被广泛应用于机器视觉照明系统，如增材制造领域的过程监测系统。照明系统的质量直接影响整个监测系统的效率和准确性。然而，现有的设计在短照明距离和具有混合多光谱通道的小检测区域无法满足光学效率和均匀性要求。因此，本文提出了一种据我们所知新颖的设计方法，即将自由曲面透镜和方形棒透镜集成在一起。对不同工作距离和目标表面类型下的光学特性进行了优化和评估。同时，利用公差分析来证明安装的可行性。使用Tracepro软件进行模拟，结果表明，所设计的复合机器视觉照明系统在250mm距离的检测区域内可获得81.704%的光学效率和95.804%的照度均匀性。此外，还对原型进行了验证实验，证明了所提出的机器视觉照明系统的可行性。
