Perspective Transformation-Based Computed Laminography for Artifact Reduction in Non-Destructive Inspection of Printed Circuit Boards

X-ray computed tomography (CT) is widely used in non-destructive testing; however, it exhibits inherent limitations when scanning objects with a large aspect ratio. Computed laminography (CL) provides an alternative solution; nevertheless, due to its distinctive scanning geometry, analytical CL reconstruction methods, such as the filtered back projection (FBP) algorithm, are prone to laminographic and superposition artifacts, thereby degrading image quality. To address this issue, a perspective transformation-based data conversion method (PT-CL-FDK) for cone-beam CL is proposed. Firstly, a virtual detector is introduced, and the perspective transformation relationship between the real and virtual detectors is derived. Secondly, the acquired CL projection data are transformed onto the virtual detector. Finally, the converted projection data are reconstructed using a CL-FDK algorithm. Simulation and real printed circuit board (PCB) experimental results demonstrate that, compared with CL-FBP, the proposed method effectively suppresses superposition artifacts and preserves object boundaries, while significantly enhancing the contrast and resolution of void defects in PCBs.