Next generation Fourier ptychographic microscopy: computational and experimental techniques

Abstract

Fourier ptychography is a recently developed computational imaging technique, which enables gigapixel image reconstruction from multiple low-resolution measurements. The technique can be implemented on simple, low-quality microscopes to achieve unprecedented image quality by exchanging optical design complexity with computational complexity. While developments have been made, demonstrations typically use well-calibrated, highperformance microscopes. Therefore, the real world performance and true benefits of(lowcost) Fourier ptychography still need to be demonstrated in out-of-lab environments where unforeseen problems are not unlikely. In this thesis, I will demonstrate how to utilise Fourier ptychography in a fast, robust and cheap manner. Two experimental prototypes will be introduced, one of them being an ultra-low-cost 3D printed microscope capable of wide-field sub-micron resolution imaging. Another prototype was built to demonstrate high-speed gigapixel imaging, capable of 100-megapixel, 1µm resolution image capture in under 3 seconds. Novel image formation models and their refinements were developed to correct the incomplete conventional model. These include partial coherence of the illumination, deviation from the plane-wave assumption, and spatially varying aberrations. Lastly, Experimental work was also heavily supplemented by novel calibration and reconstruction algorithms. Theoretical work outlined in this thesis enables the use of tilted, off-axis optical components, alleviating typically assumed parallel plane optical geometry. Optical precision requirements can also be relaxed due to novel robust calibration algorithms. As a result, low-cost 3D printed microscopes can be used

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