Scanning phase imaging without accurate positioning system

Ptychography, a high-resolution phase imaging technique using precise in-plane translation information, has been widely applied in modern synchrotron radiation sources across the globe. A key requirement for successful ptychographic reconstruction is the precise knowledge of the scanning positions, which are typically obtained by a physical interferometric positioning system. Whereas high-throughput positioning poses a challenge in engineering, especially in nano or even smaller scale. In this work, we propose a novel scanning imaging framework that does not require any prior position information from the positioning system. Specifically, our scheme utilizes the wavefront modulation mechanism to reconstruct the object functions at each scan position and the shared illumination function, simultaneously. The scanning trajectory information is extracted by our subpixel image registration algorithm from the overlap region of reconstructed object functions. Then, a completed object function can be obtained by assembling each part of the reconstructed sample functions. High-quality imaging of biological sample and position recovery with sub-pixel accuracy are demonstrated in proof-of-concept experiment. Based on current results, we find it may have great potential applications in high-resolution and high throughput phase imaging.