摘要： In this paper, an innovative monitoring system capable of diagnosing the penetration state during the laser welding process is introduced, which consists of two main blocks: a coaxial visual monitoring platform and a penetration state diagnosis unit. The platform can capture coaxial images of the interaction zone during the laser welding through a partially transmitting mirror and a high-speed camera. An image dataset representing four welding states was created for training and validation. The unit mainly consists of an embedded power-efficient computing TX2 and image processing algorithms based on a convolution neural network (CNN). Experiment results show that the platform can stably capture state-of-the-art welding images. The CNN used for a diagnosis of the penetration state is optimized using an optimal network structure and hyperparameters, applying a super-Gaussian function to initialize the weights of the convolutional layer. Its latency on TX2 is less than 2 ms, satisfying the real-time requirement. During the real laser welding of tailor-rolled blanks, a penetration state diagnosis with an accuracy of 94.6 % can be achieved even if the illumination changes significantly. The similar accuracy between the validating set and a real laser welding demonstrates that the proposed monitoring system has strong robustness. The precision and recall ratios of the CNN are higher than those of other methods such as a histogram of oriented gradients and local binary pattern.