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Iterative Time-Reversed Ultrasonically Encoded Light Focusing in Backscattering Mode

Ruan, Haowen and Jang, Mooseok and Judkewitz, Benjamin and Yang, Changhuei (2014) Iterative Time-Reversed Ultrasonically Encoded Light Focusing in Backscattering Mode. Scientific Reports, 4 (11). Art. No. 7156. ISSN 2045-2322. PMCID PMC4239564.

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The Time-Reversed Ultrasound-Encoded (TRUE) light technique enables noninvasive focusing deep inside scattering media. However, the time-reversal procedure usually has a low signal-to-noise ratio because the intensity of ultrasound-encoded light is intrinsically low. Consequently, the contrast and resolution of TRUE focus is far from ideal, especially in the backscattering geometry, which is more practical in many biomedical applications. To improve the light intensity and resolution of TRUE focus, we developed an iterative TRUE (iTRUE) light focusing technique that employs the TRUE focus itself as a signal source (rather than diffused light) for subsequent TRUE procedures. Importantly, this iTRUE technique enables light focusing in backscattering mode. Here, we demonstrate the concept by focusing light in between scattering layers in a backscattering configuration and show that the light intensity at the focus is progressively enhanced by a factor of ~20. By scanning across a fluorescent bead between these two scattering layers, the focusing resolution in the ultrasound axial and lateral directions was improved ~2-fold and ~3-fold, respectively. We further explored the application of iTRUE in biological samples by focusing light between 1 mm thick chicken tissue and cartilage, and light intensity enhancements of the same order were also observed.

Item Type:Article
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URLURL TypeDescription CentralArticle
Yang, Changhuei0000-0001-8791-0354
Additional Information:© 2014 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit Received: 30 May 2014; accepted: 5 November 2014; published: 21 November 2014. We thank Dr. Euiheon Chung, Dr. Yingmin Wang,Mr. Roarke Horstmeyer,Mr. Haojiang Zhou and Mr. Jinho Kim for helpful discussions. This work was supported by NIH 1DP2OD007307-01 and the GIST-Caltech Collaborative Research Fund. Benjamin Judkewitz is a recipient of a Sir Henry Wellcome Fellowship from the Wellcome Trust.
Funding AgencyGrant Number
GIST-Caltech Collaborative Research FundUNSPECIFIED
Sir Henry Wellcome FellowshipUNSPECIFIED
Subject Keywords:Adaptive optics; Imaging and sensing; Biophotonics; Imaging techniques
Issue or Number:11
PubMed Central ID:PMC4239564
Record Number:CaltechAUTHORS:20150108-153546749
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Official Citation:Ruan, H., Jang, M., Judkewitz, B., & Yang, C. (2014). Iterative Time-Reversed Ultrasonically Encoded Light Focusing in Backscattering Mode. [Article]. Sci. Rep., 4. doi: 10.1038/srep07156
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53405
Deposited By: Jason Perez
Deposited On:10 Jan 2015 04:03
Last Modified:09 Mar 2020 13:19

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