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Published March 2011 | Accepted Version + Supplemental Material
Journal Article Open

Time-reversed ultrasonically encoded optical focusing into scattering media


Light focusing plays a central role in biomedical imaging, manipulation and therapy. In scattering media, direct light focusing becomes infeasible beyond one transport mean free path. All previous methods used to overcome this diffusion limit lack a practical internal 'guide star'. Here, we propose and experimentally validate a novel concept called time-reversed ultrasonically encoded (TRUE) optical focusing to deliver light into any dynamically defined location inside a scattering medium. First, diffused coherent light is encoded by a focused ultrasonic wave to provide a virtual internal guide star. Only the encoded light is time-reversed and transmitted back to the ultrasonic focus. The time-reversed ultrasonically encoded optical focus—defined by the ultrasonic wave—is unaffected by multiple scattering of light. Such focusing is particularly desirable in biological tissue, where ultrasonic scattering is ~1,000 times weaker than optical scattering. Various fields, including biomedical and colloidal optics, can benefit from TRUE optical focusing.

Additional Information

© 2011 Macmillan Publishers Limited. Received 20 July 2010; accepted 26 November 2010; published online 16 January 2011. This work was sponsored in part by the National Institutes of Health (grants R01 EB000712, R01 EB008085, R01 CA134539, U54 CA136398 and 5P60 DK02057933). Author contributions: X.X. and H.L. contributed equally to the experimental design and study, Monte Carlo simulation, data analysis and writing of the manuscript. L.V.W. conceived the original idea, discussed the experiments and revised the paper. The authors declare competing financial interests: L.V.W. has a financial interest in Microphotoacoustics and Endra, which, however, did not support this work.

Attached Files

Accepted Version - nihms254850.pdf

Supplemental Material - nphoton.2010.306-s1.mov

Supplemental Material - nphoton.2010.306-s2.mov


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August 19, 2023
October 19, 2023