First Advisor

Dr. Jay Nadeau

Date of Award

Spring 6-2026

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Physics and University Honors

Department

Physics

Language

English

Subjects

quantitative phase imaging, 3D cell tracking, optical instrumentation, Fourier Reconstruction, Microbiological Motility

Abstract

Off-axis digital holographic microscopy (DHM) is a powerful tool for 3D, non-invasive live-cell tracking without moving parts. However, traditional setups face an inherent dilemma: split-path interferometers offer high spatial resolution but poor temporal stability, while more stable common-mode configurations are historically limited to lower numerical aperture (NA) regimes. This thesis bridges that gap by scaling a common-mode DHM architecture into a high-resolution benchtop instrument featuring NA = 0.65 objectives, paired with a high-power 520 nm laser source to combat transmission losses and sustain imaging frame rates across an expanded optical footprint. We map the multi-variable design space required to satisfy the Nyquist sampling criterion, examining the geometric tradeoffs of the chosen tube lens paired with a CCD sensor featuring 3.45 µm pixel pitch. Initial Fourier processing confirms successful carrier fringe generation; however, washed-out sidebands suggest high spatial frequencies are being clipped, likely due to objective output wavefronts overfilling the tube lens aperture. A digital reconstruction framework is outlined for future biological imaging, alongside a resolution analysis. This work establishes a stable proof-of-concept for translating common-mode architectures into high-resolution laboratory instruments.

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