Dissertation Talk: Coded Illumination for Multidimensional Quantitative Phase Microscopy

Seminar | May 8 | 12:30-1:30 p.m. | Soda Hall, Visual Computing Lab (VCL)

 Michael Chen, UC Berkeley

 Electrical Engineering and Computer Sciences (EECS)

Imaging biological samples under optical microscopes is challenging, since the absorption is too weak to form images with informative contrast. Besides fluorescent imaging techniques, label-free phase contrast imaging methods have been proposed to greatly improve the contrast of transparent samples. In order to efficiently recover quantitative properties, such as 2D phase projection and 3D refractive index, computational imaging frameworks that co-designs optics and post-processing algorithms need to be developed.
In this talk, I will introduce a low-cost retrofitted optical microscope, which can achieve fast 2D and 3D Quantitative Phase Imaging (QPI) of biological objects via a programmable light source. First, we will see how the phase information is captured with coded illumination. Second, a camera-limited Differential Phase Contrast (DPC) QPI method will be demonstrated using wavelength-multiplexing and enables 100fps in-vitro imaging. Third, system aberrations are simultaneously corrected during the phase retrieval process with as less as 4 measurements without additional hardware calibrations, since the pupil function can be expressed by low-dimensional Zernike coefficients. Finally, I'll introduce 3D imaging models for both weakly and multiple scattering objects, which allow simple data acquisitions and have relatively low memory/computation requirements. As a result, Giga-voxel 3D refractive index reconstruction with sub-wavelength resolution is achieved via parallel imaging processing.

 mchen0405@berkeley.edu, 650-285-7867