Patrick Ledwig
BME PhD Proposal Presentation

Date:2021-12-01
Time: 1:00 PM
Location / Meeting Link: https://bluejeans.com/619926804/0967

Committee Members:
Shu Jia, Erin Buckley, Ahmet Coskun, Thomas Gaylord, Francisco Robles


Title: Imaging beyond the single-scattering limit with quantitative oblique back-illumination microscopy

Abstract: Quantitative oblique back-illumination microscopy (qOBM) uses multiple scattering of illumination light between the source LED and the target as a source of partially coherent illumination of the target. The incoherence of the effective illumination pattern grants qOBM tomographic cross-sectioning, while providing phase contrast due to the asymmetry of the preferred direction of the sub-diffusely scattered light. This makes qOBM an effective tool for reconstructing 3D tomographic maps of index of refraction of unaltered biological specimens outside of the reach of other phase tomographic techniques. However, it must contend with multiple scattering of light between the target and the objective when imaging at a depth of more than one mean-free scattering length. This results in a gradual loss of contrast and structural information with depth. This can prevent imaging of important biological structures just below the surface, such as cell bodies in the second layer of cortical tissue in mouse brains, where important markers of neuropathology begin to appear. Aim 1: Remedy the loss of contrast with depth due to scattering in tissue between the target object and the microscope with a nonlinear spatially dependent deconvolution. Aim 2: Improve the penetration depth of qOBM by recovering deep object features with illumination diversity and iterative reconstruction to accommodate multiple scattering. Aim 3: Implement deep qOBM to image cell bodies in deeper layers of cortical tissue in a mouse model of neurodegenerative disease.