Leveraging optical scatter for complex imaging goals

Abstract

A comprehensive understanding of optical imaging in the presence of scattering media is essential for applications ranging from biomedical testing to atmospheric sensing, yet conventional imaging approaches tip toe around scattering phenomena, treating it as a phenomenon to be avoided altogether. This dissertation asserts that optical scattering can serve as both an enabling and a disabling tool for imaging, depending on the application context and imaging strategy pursued. Considering scattering as an enabling tool, I introduce how optical memory effect imaging can permit imaging behind thin scattering media, and discuss how the introduction of a pseudophase-based analysis could improve the reconstructed images. Using simulated optical data, I then show how using pseudophase in the image reconstruction step in memory effect imaging is possible, but does not provide a compelling improvement to conventional methods. Then considering scattering as a disabling tool, I introduce the idea of constructing a one-way vision environment, imposed by a cloud of oriented synthetic aerosol particles, and discuss key aspects of the project with the intent of establishing feasibility and efficacy metrics. First, I experimentally verified acoustically induced particle rotation using carbon fiber particles, observing an average rotation time of about 1.4 seconds in water when applying 205 volts to commercial off-the-shelf transducers, and found reasonable agreement with simulation. Then I introduce the optimized geometry of the bespoke microclub particle that would compose this asymmetric vision cloud, present single-particle FEM simulations, and discuss the M-matrix model of describing multiple scattering events in a cloud of oriented microclubs. And finally I describe a one-dimensional photon propagation model that I used to approximate the modulation transfer function of a plume of oriented microclub particles, and identified the absorption dominant propagation path as causing the most vision degradation. While each of these pursuits employ optical scattering to achieve different effects, both establish that imaging in the presence of scatter is a yet poorly described, high-potential mechanism for achieving complex imaging goals.