An Area Modulation Binary Defocusing-Based Digital Fringe Projection 3-D Shape Measurement Method for Print Circuit Board Inspection

Three-dimensional measurement plays a crucial role in the inspection of printed circuit board (PCB). Binary defocusing-based digital fringe projection (DFP) 3-D shape measurement method can achieve high-accuracy measurement and improve the speed of traditional DFP method, which can be widely used in virtual reality, industrial manufacturing, and so on. In this article, we propose an area modulation binary defocusing-based DFP 3-D shape measurement method for PCB inspection. To address the limitations of the 1-D modulation method, a
$16\times 4$
pixel area pattern fringe is adopted. Then, the optimal binary defocusing grating is obtained by an optimal blurred factor determination method. The accurate geometric measurement results are obtained from the high-quality 3-D point clouds. A series of experiments were conducted to evaluate the effectiveness of the proposed method. Experiment results show that the proposed method has higher phase accuracy and point cloud accuracy than the other methods. The proposed method achieves a measurement accuracy of less than 0.1 mm, surpassing other compared methods. In addition, it provides a new approach for PCB inspection.