Development of a Multi-angle Illumination Microscope for 3D Refractive Index Reconstruction

Abstract

This thesis presents the design,implementation,and evaluation of a multi-angle illumination micro- scope tailored for 3D refractive index (ri) reconstruction using the Multi-Slice Beam Propagation (msbp) method. The system combines custom-built hardware, including precision-aligned optical components and motorized kinematic mirrors, with computational algorithms developed in Python toachievehigh-resolutionimagingofcomplexbiologicalsamples. Bycalibratingilluminationangles through Fourier ptychography and optimizing experimental parameters, the system unlocks the potential for reconstruction of 3D ri distributions from intensity measurements. The developed methodology addresses challenges in adapting the msbp method for real-world applications, such as alignment precision, system calibration, and data processing. Experimental validation is performed using bead samples and a biological specimen (Peace Lily pollen), demon- stratingthesystem’scapabilitytoreconstructdetailed3Drimaps. However,itwasultimatelyfound that the iteration amount needed to be optimized to achieve better reconstruction quality. Thus the results underscore the potential of this approach for advancing label-free, high-resolution optical microscopy, while highlighting areas of improvement, paving the way for its application to complex, multiple-scattering biological samples