Multiple light scattering is considered as the major limitation for deep imaging and focusing in turbid media.In this paper,we present an innovative method to overcome this limitation and enhance the delivery of light energy ultra-deep into turbid media with significant improvement in focusing.Our method is based on a wide-field reflection matrix optical coherence tomography(RM-OCT).The time-reversal decomposition of the RM is calibrated with the Tikhonov regularization parameter in order to get more accurate reversal results deep inside the scattering sample.We propose a concept named model energy matrix,which provides a direct mapping of light energy distribution inside the scattering sample.To the best of our knowledge,it is the first time that a method to measure and quantify the distribution of beam intensity inside a scattering sample is demonstrated.By employing the inversion of RM to find the matched wavefront and shaping with a phase-only spatial light modulator,we succeeded in both focusing a beam deep(～9.6 times of scattering mean free path,SMFP)inside the sample and increasing the delivery of light energy by an order of magnitude at an ultra-deep(～14.4 SMFP)position.This technique provides a powerful tool to understand the propagation of photon in a scattering medium and opens a new way to focus light inside biological tissues.

Jing Cao;Qiang Yang;Yusi Miao;Yan Li;Saijun Qiu;Zhikai Zhu;Pinghe Wang;Zhongping Chen

Beckman Laser Institute,University of California,Irvine,Irvine,CA 92612,USA;Key Laboratory of Biomedical Engineering of Hainan Province,School of Biomedical Engineering,Hainan University,570228 Hainan,China;Department of Biomedical Engineering,University of California,Irvine,Irvine,CA 92697,USA;China State Key Laboratory of Electronic Thin Films and Integrated Devices,School of Optoelectronic Science and Engineering,University of Electronic Science and Technology of China,610054 Chengdu,China

光：科学与应用（英文版）

[1]Jing Cao;Qiang Yang;Yusi Miao;Yan Li;Saijun Qiu;Zhikai Zhu;Pinghe Wang;Zhongping Chen-.Enhance the delivery of light energy ultra-deep into turbid medium by controlling multiple scattering photons to travel in open channels)[J].光：科学与应用（英文版）,2022(05):945-954

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