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Published November 10, 2014 | Published
Journal Article Open

Frequency-swept time-reversed ultrasonically encoded optical focusing


A technique to rapidly scan an optical focus inside a turbid medium is attractive for various biomedical applications. Time-reversed ultrasonically encoded (TRUE) optical focusing has previously demonstrated light focusing into a turbid medium, using both analog and digital devices. Although the digital implementation can generate a focus with high energy, it has been time consuming to scan the TRUE focus inside a sample. Here, by sweeping the frequencies of both ultrasound and light, we demonstrate a multiplex recording of ultrasonically encoded wavefronts, accelerating the generation of multiple TRUE foci. Using this technique, we obtained a 2-D image of a fluorescent target centered inside a turbid sample having a thickness of 2.4 transport mean free paths.

Additional Information

© 2014 AIP Publishing LLC. Received 14 September 2014; accepted 5 November 2014; published online 11 November 2014. We thank J. Ballard and J. W. Tay for editing the manuscript. This work was sponsored in part by National Institutes of Health grants DP1 EB016986 (NIH Director's Pioneer Award). L.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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