Resolution enhancement of long-range imaging with sparse apertures

Synthetic aperture technique could effectively expand the passband and beyond the diffraction limit of aperture. Macroscopic Fourier ptychography (FP) makes synthetic aperture feasible in visible light by incorporating phase retrieval process into synthetic aperture. In FP, a dense aperture sampling is necessary to overcome the ill-posedness of phase retrieval, which leads to long acquisition time and heavy computation. Here, a total variation regularization-based Fourier ptychographic (TVFP) reconstruction method is proposed for long-range imaging. The TVFP method imposes total variation constraints to improve the ill-posedness of the imaging model, and recovers high-quality image from sparse aperture sampling. For the imaging system with aberration, a joint optimization of pupil function and target image is also proposed to achieve the aberration free image and the estimated pupil function simultaneously. The results show the aperture overlapping ratio could be reduced to 25% or less. The proposed method simplifies the imaging configuration and improves the robustness for long-range imaging.