Space-based correction method for LED array misalignment in Fourier ptychographic microscopy

Fourier ptychographic microscopy is a super-resolution technique, which could break through the Space-Band-Product (SBP) limit of the system by employing varied-illumination and phase retrieval algorithm. A LED array is used to provide angularly varying illuminations, which is portable and cheap. However, the installation accuracy of the LED array is not sufficient, resulting in position misalignment errors. The misalignment errors not only cause the calculation error of the sub-apertures in the frequency domain, but also the artifacts in reconstruction images. Although some correction methods have been proposed, the correction ability of these methods cannot deal with the misalignment errors well. In this paper, we proposed a misalignment errors correction method. This method uses the Particle swarm optimization (PSO) algorithm to search the four misalignment parameters (Δx, Δy, θ, Δh) in space domain. It is termed as Space based correction (SBC) method. Compared with the state-of-art methods, the SBC method is more stable and accuracy.