Date of Award
Spring 2026
Language
English
Embargo Period
4-28-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
College/School/Department
Department of Physics
Program
Physics
First Advisor
Jonathan Petruccelli
Committee Members
Jonathan Petruccelli, Alexander Khmaladze, Carolyn MacDonald, Supriya D. Mahajan Kevin Knuth
Keywords
optics, computational imaging, quantitative phase imaging, transport of intensity equation, digital holographic microscopy, optical diffraction tomography
Subject Categories
Optics
Abstract
Non-invasive imaging schemes are highly sought after methodologies in biology and metrology, where maintaining the physical state of a sample is important. Quantitative phase imaging (QPI) techniques non-invasively reconstruct the relative phase delay imparted onto an optical field due to transmission through a sample. Phase delay is proportional to the thickness and refractive index of the sample, but is lost in the intensity measurement process. Digital holographic microscopy (DHM) and transport of intensity equation (TIE) phase imaging are two high-resolution QPI techniques. DHM is a well-researched, accurate, and widely implemented technique, but can be difficult to implement in labs without optical engineering experience. TIE phase imaging is the relatively less studied QPI technique, but is more readily implementable.
In this work, TIE and DHM retrieved phase delay profiles are directly compared in a bioimaging environment. First, using sequential TIE and DHM measurements, we show that the two techniques measure quantitatively similar phase delays for a static target with known properties, as well as for a live cell. We then show, through simultaneously captured TIE and DHM phase reconstructions, that a common solution to the TIE, the fast Fourier transform solution subject to Tikhonov regularization, underestimated phase delay compared to DHM. We found that, for the purposes of tracking biomarkers throughout dynamic biological processes, the relative changes measured by TIE were robust to this discrepancy, showing excellent agreement with the biomarkers measured by DHM. TIE phase imaging was then applied to measure the total non-aqueous mass, or dry mass, distribution of C6 cells undergoing methamphetamine-induced apoptosis. We found that in early apoptosis, the dry mass of C6 cells increased slightly. Optical diffraction tomography (ODT), a tomographic imaging technique capable of reconstructing 3D refractive index distributions, and therefore dry mass density, revealed that the slight increase in dry mass coincided with a decrease in total cellular volume.
The ability of ODT to measure changes in dry mass density of apoptotic C6 cells led to the development of an in-house ODT microscope. We outline this microscope, as well as a newly derived form of the TIE, the non-paraxial TIE (NPTIE). We show a NPTIE and ODT retrieved refractive index profile for a simulated sample, demonstrating the accuracy of the technique. The refractive index profile of a live human epithelial cell reconstructed using NPTIE and ODT is also shown, thereby demonstrating its experimental capabilities.
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Carney, Shane D., "Developments and Applications of Transport of Intensity Equation Imaging and Optical Diffraction Tomography in Bioimaging" (2026). Electronic Theses & Dissertations (2024 - present). 467.
https://scholarsarchive.library.albany.edu/etd/467