Study on Optimal Laminographic Tilt Angle: A Method for Analyzing Quantity Information Gained in Projections

In laminography imaging, the laminographic tilt angle is an important factor that affects the reconstruction result. However, the optimal tilt angle was mainly estimated from experience in the current research. In this article, an estimation approach for measuring the quantity information of projections has been proposed, which is based on the entropy of pixel grayscale distribution. The correlation of reconstructed image quality and tilt angle was analyzed quantitatively by the method. In this way, a solution has been proposed for seeking the optimal tilt angle, which aims to improve the image quality of reconstructed layers. Additionally, numerical simulation was designed to validate the method, in which the reconstructed layer images at different tilt angles were compared. The curves of grayscale MAE, PSNR and SSIM versus tilt angle verified the reliability of calculated optimal tilt angle, which has proved that the method is effective. Meanwhile, given a certain model of the scanned object, the optimal tilt angle is constant and computable.