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Ptychography is a lensless imaging technique that is capable of reconstructing an object and illumination simultaneously by scanning the object at several positions with respect to a localized illumination beam. It has emerged as a powerful tool with applications ranging from high resolution imaging to optical metrology. A precise image reconstruction in ptychography is of utmost importance in several applications. An error in the measurement of the object–detector distance was found to affect the reliability of the reconstructed probe and the object. Several axial distance correction algorithms have been proposed to address the issue. However, the additional axial distance correction increases the complexity of the reconstruction algorithm. In this study, a detailed theoretical analysis of the relationship between the reconstructed images and the object–detector distance error is presented. It shows that high resolution object and probe images can still be reconstructed without an axial distance correction algorithm. The theoretical analysis is quantitatively studied by numerical simulations and experimental results.

Based on the wavefront sensing and propagation, the wavefront-based autofocus approach is proposed for potentially adopted in rapid autofocusing since it can precisely locate the focal plane but only requiring much fewer multi-focal image captures. However, due to the much time spent in serial numerical calculation and analysis, this method fails to improve the autofocusing efficiency as expected. In order to further accelerate the autofocusing speed, we improve this method by adopting the parallel computing in the numerical wavefront propagation and focal analysis procedures based on the graphics processing unit (GPU). Proved by experiments relying on our self-built system, the time consuming for autofocusing can be drastically reduced within 1 s, besides, it can guarantee extremely high focal determination accuracy in various sample cases, indicating that the GPU aided wavefront-based method can be future adopted in commercial microscopes for precise and rapid autofocusing.

The recently developed Light Field Moment Imaging (LMI) is adopted to show the stereoscopic structure of the sample studied in Coherent Diffractive Imaging (CDI), where 3D image were always generated with complicated experimental procedure such as the rotation of the sample and time-consuming computation. The animation of large view angle can be generated with LMI very quickly, and the 3D structure of sample can be shown vividly. This method can find many applications for the coherent diffraction imaging with x-ray and electron beams, where a glimpse of the hierarchical structure required and the quick and simple 3D view of object is sufficient. The feasibility of this method is demonstrated theoretically and experimentally with a recently developed CDI method called Ptychographic Iterative Engine.