VA & Opt Webinar: Hieu Thao Nguyen (TU Delft)

Title:  Projection Algorithms for Phase Retrieval with High Numerical Aperture

Speaker: Hieu Thao Nguyen (TU Delft)

Date and Time: August 19th, 2020, 17:00 AEST (Register here for remote connection via Zoom)

Abstract: We develop the mathematical framework in which the class of projection algorithms can be applied to high numerical aperture (NA) phase retrieval. Within this framework we first analyze the basic steps of solving this problem by projection algorithms and establish the closed forms of all the relevant prox-operators. We then study the geometry of the high-NA phase retrieval problem and the obtained results are subsequently used to establish convergence criteria of projection algorithms. Making use of the vectorial point-spread-function (PSF) is, on the one hand, the key difference between this work and the literature of phase retrieval mathematics which mostly deals with the scalar PSF. The results of this paper, on the other hand, can be viewed as extensions of those concerning projection methods for low-NA phase retrieval. Importantly, the improved performance of projection methods over the other classes of phase retrieval algorithms in the low-NA setting now also becomes applicable to the high-NA case. This is demonstrated by the accompanying numerical results which show that all available solution approaches for high-NA phase retrieval are outperformed by projection methods.