Fast automatic multiple positioning for lensless coherent diffraction imaging

The distance errors in coherent diffraction imaging degrade reconstructed images. In this paper, a fast autopositioning algorithm based on subdivision search is proposed to calculate the position of each image. The search scheme can obtain diffraction distances quickly and accurately. For the same range and search accuracy, the calculation speed of one pattern in this method is approximately 30 times that of the traversal search algorithm. The proposed strategy recording patterns with increasing intervals improves the convergence of iterative phase retrieval. The recovered images are high quality since the influence of ripple waves is limited. This method is beneficial to the robustness and flexibility of multi-distance computational imaging.