Coded Ptychographic Imaging

Ptychography was originally proposed to solve the phase problem in electron crystallography. In the past decade, it has evolved into an enabling imaging technique for both fundamental and applied sciences. This chapter discusses the background and implementations relevant to high-resolution optical imaging using ptychography. It begins with a brief overview of the phase retrieval concept and the ptychography technique. Subsequently, it focuses on the information encoding process in ptychography and discusses two strategies for high-resolution optical imaging, namely coded illumination and coded detection. For coded illumination, we present the Fourier ptychography approach that uses angle-varied plane waves for wide-field, high-resolution imaging. For coded detection, we present the lensless coded ptychography approach that uses a coded image sensor for high-throughput optical imaging. These two approaches can address the intrinsic trade-off between resolution and field of view of an optical system, thereby offering new opportunities for biomedical imaging in the visible light regime. For both approaches, we provide a detailed procedure for implementing ptychographic reconstruction and discuss how to avoid the most common pitfalls encountered in the experiments. The related biomedical applications and concept extensions are also discussed. Finally, we outline several perspectives for future development.