Multi-slice coded coherent diffraction imaging

Coded coherent diffraction imaging (CDI) introduces wavefront modulation to realize full-field phase retrieval, without mechanical scanning as in ptychography. The conventional coded CDI relies on the assumption of thin samples, which breaks down when handling thick objects with multiple scattering and diffraction effects. In this study, we report a multi-slice coded CDI technique that enables to reconstruct thick objects with high fidelity. The object is modeled as a group of multiple slices, and the wavefront exiting the object is calculated after slice-to-slice propagation. We develop an optimization algorithm to simultaneously reconstruct multiple complex-field slices, as well as the slice distances. This enables successful reconstruction without the prior knowledge of slice separations that is hard to calibrate. Experimental results show that reconstruction of more slices can be achieved by increasing the number of modulations. The required modulation number is 7 for 2-slice objects, 14 for 3-slice objects, and 20 for 4-slice objects. Unknown slice distance that is at most ∼±30% deviating from the groundtruth can be effectively corrected.