Single-molecule tracking (SMT) inside the cell nucleus is a powerful approach to probe DNA repair mechanisms and transcription factor (TF) regulation at the nanoscale. A central limitation in high-NA objectives necessary for single-molecule microscopy is the short depth of focus (DoF), which causes tracked molecules to leave focus prematurely, shortening trajectories and biasing dynamic readouts. This internship aims to extend the depth of focus in single-molecule localization microscopy (SMLM) and SMT without sacrificing photons by using a deformable mirror (DM) at a pupil- conjugate plane to implement smooth, phase-only masks. The goal is to achieve 2x-5x axial PSF extension with minimal lateral broadening so that single emitters remain observable for longer, enabling longer, less-biased SMT traces in the nucleus.