Coherence Retrieval and Multi-contrast Microscopy Imaging by Transport of Intensity Stack

We report a new coherence retrieval method based on transport of intensity stack. We capture intensity images at different focal planes, corresponding to phase-space shearing projection, into four-dimensional (4D) phase space to create both high spatial and spatial frequency resolution phase space. We represent the optical field of an arbitrary coherent mode with the help of a typical function in phase space, i.e., the Wigner distribution function. Previous studies mainly focus on coherence measurement by means of interferometry. In addition, despite the sacrifice of both spatial and spatial frequency resolution, wavefront sensor is also a standard tool for coherence measurement. To overcome the existing problems, our method only requires z-scanning to achieve fullresolution coherent retrieval of the optical field without interferometric detection. Furthermore, without requiring hardware modifications, we introduced our coherence retrieval method into microscopic imaging. We apply our method to multi-contrast microscopic imaging with only intensity stack, which have the potential to allow clinicians to view a sample with three separate contrast methods at once, enhancing the information available for diagnosis and disease discrimination.