Microscope lenses can have either large field of view (FOV) or high resolution, not both. Fourier ptychographic microscopy (FPM) is a new computational microscopy technique that circumvents this limit by fusing information from multiple images taken with different illumination angles. The result is a Gigapixel-scale image having both wide FOV and high resolution, i.e. large space-bandwidth product. FPM has enormous potential for revolutionizing microscopy and has already found application in digital pathology. However, it suffers from long acquisition times (on the order of minutes), limiting throughput. Faster capture times would not only improve imaging speed, but also allow studies of live samples, where motion artifacts degrade results. Here, we present a new source coding scheme to improve the acquisition time by several orders of magnitude, enabling high space-bandwidth-time product imaging. We demonstrate our high-speed Gigapixel phase microscopy method by imaging both growing and confluent in vitro cell cultures, capturing videos of subcellular dynamical phenomena in popular cell lines undergoing division and migration. Further, we extend the Gigapixel imaging capability to 3D by processing 4D light field measurements from sequential illumination scanning. Starting from geometric optics light field refocusing, we incorporate phase retrieval and correct diffraction artifacts using a multislice coherent model that accounts for multiple scattering. Further, we incorporate dark-field images to achieve lateral resolution beyond the diffraction limit of the objective (5× larger NA) and optical sectioning better than the depth of field, using a low-magnification objective with a large FOV.
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Lei Tian and Laura Waller
High-speed gigapixel and 3D phase microscopy using coded illumination (Conference Presentation)
", Proc. SPIE 9713, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXIII, 97130T (March 15, 2016); doi:10.1117/12.2220312; http://dx.doi.org/10.1117/12.2220312