{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/112919"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/112919","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"High Resolution Phase Imaging using Transport of Intensity Equation","abstract":"Quantitative phase Imaging(QPI) has emerged as a valuable tool for imaging specimens with weak scattering and absorbing abilities such as cells and tissues. It is complementary to fluorescence microscopy, as such, it can be applied to unlabelled specimens without the need for fluorescent tagging. By quantitatively mapping the phase changes induced in the incident light field by the optical path length delays of the specimen, QPI provides objective measurement of the cellular dynamics and enables imaging the specimen with high contrast. Transport of Intensity Equation(TIE) is a powerful computational tool for QPI because of its experimental and computational simplicity. Using TIE, the phase can be quantitatively retrieved from defocused intensity images. However, the resolution of the phase image computed using TIE is limited by the diffraction limit of the imaging system used to capture the intensity images. In this thesis, we have developed a super resolution phase imaging technique by applying the principles of Structured Illumination Microscopy(SIM) to Transport of Intensity phase retrieval. The modulation from the illumination shifts the high frequency components of the phase object into the system pass-band. This enables phase imaging with resolutions exceeding the diffraction limit. The proposed method is experimentally validated using a custom-made upright microscope. Because of its experimental and computational simplicity, the method in this thesis should find application in biomedical laboratories where super resolution phase imaging is required","abstract_html":"Quantitative phase Imaging(QPI) has emerged as a valuable tool for imaging specimens with weak scattering and absorbing abilities such as cells and tissues. It is complementary to fluorescence microscopy, as such, it can be applied to unlabelled specimens without the need for fluorescent tagging. By quantitatively mapping the phase changes induced in the incident light field by the optical path length delays of the specimen, QPI provides objective measurement of the cellular dynamics and enables imaging the specimen with high contrast. Transport of Intensity Equation(TIE) is a powerful computational tool for QPI because of its experimental and computational simplicity. Using TIE, the phase can be quantitatively retrieved from defocused intensity images. However, the resolution of the phase image computed using TIE is limited by the diffraction limit of the imaging system used to capture the intensity images. In this thesis, we have developed a super resolution phase imaging technique by applying the principles of Structured Illumination Microscopy(SIM) to Transport of Intensity phase retrieval. The modulation from the illumination shifts the high frequency components of the phase object into the system pass-band. This enables phase imaging with resolutions exceeding the diffraction limit. The proposed method is experimentally validated using a custom-made upright microscope. Because of its experimental and computational simplicity, the method in this thesis should find application in biomedical laboratories where super resolution phase imaging is required","abstract_has_math":false,"creators":["Shanmugavel, Sibi Chakravarthy"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Electrical Engineering","degree_department":"Electrical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Zhu, Yunhui"],"committee_members":["Zhu, Yizheng","Xu, Yong"],"year":2021,"date_issued":"2021-06-23","date_published":"2021-06-23","updated_at":"2026-07-22T22:20:03Z","subjects":["Quantitative Phase Imaging","Super resolution imaging","Structured Illumination"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:31181"],"render_values":[{"text":"vt_gsexam:31181","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/112919","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Zhu, Yunhui"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Zhu, Yizheng","Xu, Yong"]},{"key":"dc:contributor.department","label":"Department","values":["Electrical Engineering"]},{"key":"dc:creator","label":"Author","values":["Shanmugavel, Sibi Chakravarthy"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2022-12-16T07:00:24Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2022-12-16T07:00:24Z"]},{"key":"dc:date.issued","label":"Date","values":["2021-06-23"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Quantitative Phase Imaging","Super resolution imaging","Structured Illumination"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:31181"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/112919"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Quantitative phase Imaging(QPI) has emerged as a valuable tool for imaging specimens with weak scattering and absorbing abilities such as cells and tissues. It is complementary to fluorescence microscopy, as such, it can be applied to unlabelled specimens without the need for fluorescent tagging. By quantitatively mapping the phase changes induced in the incident light field by the optical path length delays of the specimen, QPI provides objective measurement of the cellular dynamics and enables imaging the specimen with high contrast. Transport of Intensity Equation(TIE) is a powerful computational tool for QPI because of its experimental and computational simplicity. Using TIE, the phase can be quantitatively retrieved from defocused intensity images. However, the resolution of the phase image computed using TIE is limited by the diffraction limit of the imaging system used to capture the intensity images. In this thesis, we have developed a super resolution phase imaging technique by applying the principles of Structured Illumination Microscopy(SIM) to Transport of Intensity phase retrieval. The modulation from the illumination shifts the high frequency components of the phase object into the system pass-band. This enables phase imaging with resolutions exceeding the diffraction limit. The proposed method is experimentally validated using a custom-made upright microscope. Because of its experimental and computational simplicity, the method in this thesis should find application in biomedical laboratories where super resolution phase imaging is required"]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Transport of Intensity Equation is a quantitative phase microscopy technique that enables imaging thin transparent specimens with high phase contrast using a through focus intensity stack. It provides speckle free imaging, compatibility with bright field microscopes and valid under partial coherence. However, the Optical Transfer Function(OTF) of the imaging system or the microscope acts a low pass filter, effectively limiting the maximum spatial frequency that can pass through the system. This reduces the spatial resolution of the computed phase image to the spatial diffraction limit. There has been a continuous drive to develop Super resolution techniques that will provide sub-diffraction resolutions because it will provide better insight into the cellular structure, morphology and composition. Structured Illumination Microscopy(SIM) is one such established technique. Existing work in super resolution phase imaging using SIM is exclusively limited to holography and interferometry based techniques. However, such methods require two-beam interference, illumination sources with high coherence, high experimental stability and phase unwrapping in the postprocessing step to retrieve the true object phase. In this work, we demonstrate a single beam propagation based super resolution phase imaging technique by applying structured illumination to Transport of Intensity Equation. It is valid under partial coherence, and does not require interference, simplifying the experimental and computational requirement. We have designed an upright microscope to demonstrate high resolution phase imaging of human cheek cells."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["High Resolution Phase Imaging using Transport of Intensity Equation"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Zhu, Yunhui"],"dc:contributor.committeemember":["Zhu, Yizheng","Xu, Yong"],"dc:contributor.department":["Electrical Engineering"],"dc:creator":["Shanmugavel, Sibi Chakravarthy"],"dc:date.accessioned":["2022-12-16T07:00:24Z"],"dc:date.available":["2022-12-16T07:00:24Z"],"dc:date.issued":["2021-06-23"],"dc:description.abstract":["Quantitative phase Imaging(QPI) has emerged as a valuable tool for imaging specimens with weak scattering and absorbing abilities such as cells and tissues. It is complementary to fluorescence microscopy, as such, it can be applied to unlabelled specimens without the need for fluorescent tagging. By quantitatively mapping the phase changes induced in the incident light field by the optical path length delays of the specimen, QPI provides objective measurement of the cellular dynamics and enables imaging the specimen with high contrast. Transport of Intensity Equation(TIE) is a powerful computational tool for QPI because of its experimental and computational simplicity. Using TIE, the phase can be quantitatively retrieved from defocused intensity images. However, the resolution of the phase image computed using TIE is limited by the diffraction limit of the imaging system used to capture the intensity images. In this thesis, we have developed a super resolution phase imaging technique by applying the principles of Structured Illumination Microscopy(SIM) to Transport of Intensity phase retrieval. The modulation from the illumination shifts the high frequency components of the phase object into the system pass-band. This enables phase imaging with resolutions exceeding the diffraction limit. The proposed method is experimentally validated using a custom-made upright microscope. Because of its experimental and computational simplicity, the method in this thesis should find application in biomedical laboratories where super resolution phase imaging is required"],"dc:description.abstractgeneral":["Transport of Intensity Equation is a quantitative phase microscopy technique that enables imaging thin transparent specimens with high phase contrast using a through focus intensity stack. It provides speckle free imaging, compatibility with bright field microscopes and valid under partial coherence. However, the Optical Transfer Function(OTF) of the imaging system or the microscope acts a low pass filter, effectively limiting the maximum spatial frequency that can pass through the system. This reduces the spatial resolution of the computed phase image to the spatial diffraction limit. There has been a continuous drive to develop Super resolution techniques that will provide sub-diffraction resolutions because it will provide better insight into the cellular structure, morphology and composition. Structured Illumination Microscopy(SIM) is one such established technique. Existing work in super resolution phase imaging using SIM is exclusively limited to holography and interferometry based techniques. However, such methods require two-beam interference, illumination sources with high coherence, high experimental stability and phase unwrapping in the postprocessing step to retrieve the true object phase. In this work, we demonstrate a single beam propagation based super resolution phase imaging technique by applying structured illumination to Transport of Intensity Equation. It is valid under partial coherence, and does not require interference, simplifying the experimental and computational requirement. We have designed an upright microscope to demonstrate high resolution phase imaging of human cheek cells."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:31181"],"dc:identifier.uri":["http://hdl.handle.net/10919/112919"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Quantitative Phase Imaging","Super resolution imaging","Structured Illumination"],"dc:title":["High Resolution Phase Imaging using Transport of Intensity Equation"],"dc:type":["Thesis"],"thesis:degree_discipline":["Electrical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:03Z"}