High-performance phase imaging based on scanning modulation

The coherent diffraction imaging method with three-dimensional spiral scanning is proposed for removal of an illumination background, high contrast and a wide field-of-view (FOV) with a limited amount of data. The pattern is moved in a conical spiral rather than axial multi-height measurements or lateral translation. In this way, each intensity pattern has axial and transverse phase modulation. Firstly, we can obtain the reconstructed object without an illumination background, which decreases the background noise and increases the contrast. Secondly, the image alignment process is omitted. In multi-height phase retrieval, image alignment is a key step. Once the consequence of alignment is imprecision, the image will fail to be reconstructed. Finally, the open illumination is employed so that a wide FOV can be obtained with several patterns. Compared with typical ptychography, the proposed method uses minimal patterns to realize the same size of FOV, which reduces the time required for data acquisition and processing. Overall, the proposed method combines the advantages of multi-height measurements and ptychography, which achieves a wide FOV, removing background, high contrast and high resolution at the same time. For pathological imaging, this method can perform label-free phase imaging, and it can directly obtain large-FOV imaging without the need for image stitching technology. Finally, this method provides a new method for medical pathological microscopy imaging.