Multi-rotation coherent imaging by a phase mask

A high-efficiency coherent imaging system is designed by using phase modulation. After rotating a known phase mask, three images from rotation modulation are recorded and utilized to accurately reconstruct the complex-value sample. Specially, the system is free from rotation angle calculation, and requires fewer intensity measurements. This method has a superiority in convergence speed and calculation time. Furthermore, the optimal sample-to-sensor distance is searched by auto-focusing criteria. The proposed method is promising for compact biomedicine imaging and 3D measurement.