Correction algorithm for misalignment and magnification difference of focused and defocused images in phase diversity image reconstruction

Phase diversity (PD) technology typically requires additional optical channels to capture images with known aberrations. In real applications, defocus aberration is widely used, and a typical method is to add an imaging camera with known optical path differences from the focal plane. However, the method of introducing defocus aberration through optical path differences can lead to misalignment and different magnifications of focused and defocused images, resulting in a significant decrease in the reconstruction accuracy of the PD algorithm. In this paper, we analyze the sources of magnification difference and misalignment and propose the method based on image coordinate transformation. For simulation experiments of 400 groups, the PV values of magnification and misalignment calculation errors are 0.0008 and 1.34 pixels, which verify the accuracy of our method for image correction. For the actual extended target images, by using our method of PD technology, we achieve a reconstruction result of 1.043 times the diffraction limit, and the experimental results demonstrate the effectiveness and reliability of our method.