电路板CT成像伪影校正方法研究

In recent years, X-ray three-dimensional microscopic imaging technology is becoming more and more popular in applications like PCB spatial structure analysis, defect detection and size measurement. But there still exist many problems that need to be solved in practical PCB CT imaging, which include: image information aliasing caused by incomplete CT scanning data, and metal artifacts caused by high absorbers. These information aliasing and artifacts will lead to structural distortion in the reconstructed CT images, such that the defects in the PCB cannot be correctly identified, which will reduce the usability of the PCB CT image and limit the application scope of the micro-CT equipment. In this project, based on our previous work on dual-spectrum CT imaging and limited-angle CT imaging, we will carry out the research on the key theoretical and technical issues of limited-angle dual-spectrum CT imaging, including the spectrum data acquisition technology for tabular objects, the accurate spectrum estimation based on detector unit and the limited-angle dual-spectrum CT imaging algorithm. We aim at providing an effective and systematic method to correct the information aliasing and metal artifact in the CT images of PCB. The research results of this project can provide theoretical and technical support for the development of X-ray three-dimensional microscopic computer laminography for electronic product detection.

近年来，X射线三维显微CT成像技术在电路板空间结构分析、缺陷检测和尺寸测量等应用中发挥了越来越重要的作用。但目前，电路板CT成像仍存在不少问题亟待解决，主要包括：电路板CT扫描数据不完全引起的图像信息混叠；金属等高吸收物引起的金属伪影。这些信息混叠和伪影将导致CT图像中电路板的结构信息或缺陷信息发生畸变，影响电路板CT图像的可用性，限制显微CT设备的应用范围。本项目结合双能谱CT成像与有限角CT成像的研究基础，开展有限角双能谱CT成像的关键理论和技术问题的研究，包括针对板状物体的能谱数据获取技术、基于探测器单元的能谱精确估计和有限角双能谱CT成像算法等。最终为校正电路板CT图像中信息混叠和金属伪影提供一种有效、系统的解决方法。本项目的研究成果可为电子产品检测专用的X射线显微三维分层成像检测设备研制提供理论和技术支持。

近年来，X射线三维显微成像技术在电路板的空间结构分析、缺陷检测和尺寸测量等方面的应用越来越多。但在传统的成像条件下，重建的PCB图像上经常存在不同程度的伪影和噪声，难以满足实际应用需求。本项目围绕电路板CT成像中的伪影和噪声问题，研究了滤波器的优化设计；探测器单元的等效能谱估计；有限角双能谱CT重建算法。项目主要研究成果为：a) 提出了一种“虚拟”滤波器设计思想，并基于该思想提出了两种金属校正方法，对含不同种类材料的电路板，均能够获得较好的金属伪影校正效果；b) 基于单能X射线装置，完成了一系列常见树脂材料的衰减系数测量，为等效能谱的准确测量提供了标准材料和参考数据；c) 针对电路板CT扫描角度受限的问题，提出了几种不同的重建算法，改善了有限角伪影和噪声去除效果。该项目研究结果对于X射线成像技术在电路板CT检测领域的应用拓展和电路板专用CT检测设备研发具有重要的推动作用。