In scattering media such as biological tissue, the heterogeneous refractive index distribution causes light to scatter, which makes the media look opaque and prevents us from focusing light beyond ~1 mm deep inside the media to achieve optical imaging and manipulation. Hence, the ability to focus light deep inside scattering media is highly desired, and it could revolutionize biophotonics by enabling deep-tissue non-invasive high-resolution optical microscopy, optical tweezing, optogenetics, micro-surgery, and phototherapy.
To break the optical diffusion limit and focus light deep inside scattering media, optical phase conjugation based wavefront shaping techniques, such as time-reversed ultrasonically encoded (TRUE) optical focusing, are being actively developed. In this dissertation, I will describe our efforts to improve the performance (speed, focusing quality and focusing depth) of optical phase conjugation for future in vivo applications. Remarkably, we have focused light through tissue-mimicking phantoms up to 96 mm thick, and through ex vivo chicken breast tissue up to 25 mm thick.
","abstract_html":"<p>In scattering media such as biological tissue, the heterogeneous refractive index distribution causes light to scatter, which makes the media look opaque and prevents us from focusing light beyond ~1 mm deep inside the media to achieve optical imaging and manipulation. Hence, the ability to focus light deep inside scattering media is highly desired, and it could revolutionize biophotonics by enabling deep-tissue non-invasive high-resolution optical microscopy, optical tweezing, optogenetics, micro-surgery, and phototherapy.</p><p>To break the optical diffusion limit and focus light deep inside scattering media, optical phase conjugation based wavefront shaping techniques, such as time-reversed ultrasonically encoded (TRUE) optical focusing, are being actively developed. In this dissertation, I will describe our efforts to improve the performance (speed, focusing quality and focusing depth) of optical phase conjugation for future in vivo applications. Remarkably, we have focused light through tissue-mimicking phantoms up to 96 mm thick, and through ex vivo chicken breast tissue up to 25 mm thick.</p>","abstract_has_math":false,"creators":["Liu, Yan"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Biomedical Engineering","degree_department":null,"school":null,"contributors":["Lihong V. Wang","Samuel Achilefu, Mark Anastasio, Timothy Holy, Jung-Tsung Shen"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-12-15T08:00:00Z","date_published":"2016-12-15T08:00:00Z","updated_at":"2026-07-24T06:13:05Z","subjects":["Adaptive optics","Focusing light inside scattering media","Imaging through turbid media","Optical phase conjugation","Time reversal","Time-reversed ultrasonically encoded (TRUE) optical focusing","Engineering"],"languages":["English (en)"],"rights":["I have not registered my thesis with the U.S. Copyright Office, and do not intend to."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://openscholarship.wustl.edu/eng_etds/208"],"render_values":[{"text":"https://openscholarship.wustl.edu/eng_etds/208","href":"https://openscholarship.wustl.edu/eng_etds/208","code":true}]}]},"links":{"outbound_url":"https://doi.org/10.7936/K7PV6HSV","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lihong V. Wang","Samuel Achilefu, Mark Anastasio, Timothy Holy, Jung-Tsung Shen"]},{"key":"dc:creator","label":"Author","values":["Liu, Yan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2017-06-29T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biomedical Engineering","McKelvey School of Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Adaptive optics","Focusing light inside scattering media","Imaging through turbid media","Optical phase conjugation","Time reversal","Time-reversed ultrasonically encoded (TRUE) optical focusing","Engineering"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English (en)"]},{"key":"dc:rights","label":"Dc Rights","values":["I have not registered my thesis with the U.S. Copyright Office, and do not intend to."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.7936/K7PV6HSV","https://openscholarship.wustl.edu/eng_etds/208"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Permanent URL: https://doi.org/10.7936/K7PV6HSV"]},{"key":"dc:description.abstract","label":"Abstract","values":["In scattering media such as biological tissue, the heterogeneous refractive index distribution causes light to scatter, which makes the media look opaque and prevents us from focusing light beyond ~1 mm deep inside the media to achieve optical imaging and manipulation. Hence, the ability to focus light deep inside scattering media is highly desired, and it could revolutionize biophotonics by enabling deep-tissue non-invasive high-resolution optical microscopy, optical tweezing, optogenetics, micro-surgery, and phototherapy.
To break the optical diffusion limit and focus light deep inside scattering media, optical phase conjugation based wavefront shaping techniques, such as time-reversed ultrasonically encoded (TRUE) optical focusing, are being actively developed. In this dissertation, I will describe our efforts to improve the performance (speed, focusing quality and focusing depth) of optical phase conjugation for future in vivo applications. Remarkably, we have focused light through tissue-mimicking phantoms up to 96 mm thick, and through ex vivo chicken breast tissue up to 25 mm thick.
"]},{"key":"dc:title","label":"Title","values":["Focusing Light Inside Scattering Media with Optical Phase Conjugation"]}]}],"canonical_facts":{"dc:contributor":["Lihong V. Wang","Samuel Achilefu, Mark Anastasio, Timothy Holy, Jung-Tsung Shen"],"dc:creator":["Liu, Yan"],"dc:date.available":["2017-06-29T07:00:00Z"],"dc:description":["Permanent URL: https://doi.org/10.7936/K7PV6HSV"],"dc:description.abstract":["In scattering media such as biological tissue, the heterogeneous refractive index distribution causes light to scatter, which makes the media look opaque and prevents us from focusing light beyond ~1 mm deep inside the media to achieve optical imaging and manipulation. Hence, the ability to focus light deep inside scattering media is highly desired, and it could revolutionize biophotonics by enabling deep-tissue non-invasive high-resolution optical microscopy, optical tweezing, optogenetics, micro-surgery, and phototherapy.
To break the optical diffusion limit and focus light deep inside scattering media, optical phase conjugation based wavefront shaping techniques, such as time-reversed ultrasonically encoded (TRUE) optical focusing, are being actively developed. In this dissertation, I will describe our efforts to improve the performance (speed, focusing quality and focusing depth) of optical phase conjugation for future in vivo applications. Remarkably, we have focused light through tissue-mimicking phantoms up to 96 mm thick, and through ex vivo chicken breast tissue up to 25 mm thick.
"],"dc:identifier":["https://doi.org/10.7936/K7PV6HSV","https://openscholarship.wustl.edu/eng_etds/208"],"dc:language":["English (en)"],"dc:rights":["I have not registered my thesis with the U.S. Copyright Office, and do not intend to."],"dc:subject":["Adaptive optics","Focusing light inside scattering media","Imaging through turbid media","Optical phase conjugation","Time reversal","Time-reversed ultrasonically encoded (TRUE) optical focusing","Engineering"],"dc:title":["Focusing Light Inside Scattering Media with Optical Phase Conjugation"],"thesis:degree_discipline":["Biomedical Engineering","McKelvey School of Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T06:13:05Z"}