Sub-micron Assembly Alignment Detection Method and System Based on Optical Diffraction

With the continuous development of manufacturing technology, precision instruments are increasingly moving towards miniaturization, precision, and integration. The assembly accuracy of the product has become a critical factor that limits the performance of the product. Assembly alignment is a significant part of the assembly process, and the accuracy of alignment detection has a significant effect on the final assembly accuracy of the product. Currently, the mainstream technology is to recognize and detect the final image of two parts using microscopic visual inspection technology. However, this method struggles to achieve sub-micron level alignment detection accuracy. In this paper, we presented a sub-micron alignment detection system based on optical diffraction, and the factors influencing the detection accuracy are analysed. Based on this, an experimental assembly alignment detection system was designed based on piezoelectric ceramic drive, laser confocal sensor monitoring feedback, and the mapping relationship between the nanoscale moving position of the diffraction aperture and the diffraction result to achieve sub-micron displacement detection. In addition, experimental tests have been carried out to verify the feasibility of this program. The experimental results indicate that the developed alignment detection method and system can achieve sub-micron alignment detection accuracy, providing a novel device and development concept for high-precision assembly alignment detection.