Lensless quantitative microscopy based on multi-angle illumination and coded ptychographic phase retrieval.

Coded ptychography (CP) enables high-resolution, large field-of-view (FOV) imaging of complex objects. However, conventional CP struggles to recover low-frequency phase components, as these cannot be effectively converted into detectable intensity variations through coded image sensor translation, limiting reconstruction fidelity. Here, we report a novel lensless microscopy method that integrates multi-angle illumination with coded ptychographic phase retrieval. In this platform, the tube lens is laterally translated to generate angle-varied plane waves as phase diversity measurements, while a coded image sensor beneath the object captures the resulting diffraction patterns. The spatial modulation provided by the coded layer imposes support constraints for quantitative phase recovery. To address the issue of positioning accuracy, we directly recover the incident beam angles from the captured images. To overcome the challenge of restoring the slow-varying phase contents with multiple 2π wraps, we conduct a calibration experiment to characterize the transmission profile of the coded layer, providing deterministic constraints for the phase retrieval process. We validate the proposed approach using various samples. The approach achieves a 5.6 mm by 7.4 mm FOV with a half-pitch resolution of 0.96 μm. It offers a large FOV, high-resolution, and quantitative on-chip microscopy, making it adaptable for applications in point-of-care, global health, and telemedicine.