Thesis Title: Quantitative Phase Imaging: Instrumentation, Validation, and Annular Illumination

Committee members: Dr. Thomas K. Gaylord, Dr. Stephen E. Ralph, Dr. Wenshan Cai, Dr. Sorin Tibuleac, and Dr. Yijun Bao

Summary: The imaging of transparent objects like biological cells and optical fibers is difficult using conventional optical microscopy. Quantitative Phase Imaging (QPI) provides a label-free, quantitative, and reliable way of imaging transparent objects. Conventionally, disk illumination has been widely used as a standard illumination type in microscopy. However, annular illumination provides a way to enhance contrast and improve resolution. In this work, the phase recovery performance of the two illumination types was compared using 2D QPI experiments performed on a standard-type phase test chart using weighted-least squares multifilter phase imaging with partially coherent light (WLS-MFPI-PC). A state-of-the-art QPI system with 2D QPI and 3D QPI capabilities was developed for performing the experiments and is described in detail. The reconstructed phase images were compared to an ideal image using spatial frequency response. Furthermore, the comparison results were found to match the theoretical predictions from MFPI-PC showing the significant advantage of annular illumination in higher spatial frequencies. Thus, the model used to describe the optics of QPI for the two illumination types was validated. A summary of the paraxial, non-paraxial, and WLS-MFPI-PC theories is also provided for the readers.