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Focusing Deep inside Tissue with Time-Reversed Photons

发布日期:2015-01-04 11:18:46      浏览次数:

 Time: 10:00-11:00, Tuesday, Jan. 6th

 Venue: 104RM. Center for Biomedical Imaging, Tsinghua University

Presenter: Cheng Ma


Abstract:

Biomedical optical imaging (confocal microscopy, two-photon microscopy, and optical coherence tomography, etc.) offers rich tissue contrast, but is limited to depths within ~1 mm in the skin. The major impediment to deep penetration is the light scattering stemming from the microscopic refractive index inhomogeneities inherent to biological tissue: At a depth of 1 millimeter below the skin surface, photons are scattered more than 10 times on average, rendering their propagation completely random. The rapidly developing field—wavefront engineering—aims at suppressing light scattering by invoking optical time reversal, and shows great potential in transitioning biomedical optics into clinical practice [1]. In this talk, I will present some of our latest contributions to this exciting field. These include employing intrinsic motions for non-invasive imaging of dynamic objects [2], and using ultrasound to quickly guide light focusing [3], all inside highly scattering media. These accomplishments are expected to have profound impact on deep tissue imaging and therapy. I will conclude with a discussion on the main challenges being faced and their potential solutions.

 

References:

[1]   P. Mosk, A. Lagendijk, G. Lerosey, and M. Fink, "Controlling waves in space and time for imaging and focusing in complex media," Nature Photonics 6, 283-292 (2012).

[2]   C. Ma, X. Xu, Y. Liu, and L. V. Wang, "Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media," Nature Photonics, doi:10.1038/nphoton. 2014.251 (2014).

[3]   Y. Liu, P. Lai, C. Ma, X. Xu, A. A. Grabar and L. V. Wang, Optical focusing deep inside dynamic scattering media with time-reversed ultrasonically encoded (TRUE) light, Nature Communications, in press.

 

Biographical sketch:

Cheng Ma received his B.S. degree in Electronic Engineering from Tsinghua University, Beijing, China in 2004.  He obtained his Ph. D. degree in Electrical Engineering from Virginia Tech, Virginia, USA in 2012. His graduate research focused on developing novel optical sensors and sensing systems based on spectral interferometry, absorption spectroscopy, and optomechanical resonance. From 2012 to present, he worked as a postdoctoral researcher in the Department of Biomedical Engineering at Washington University in St Louis, Missouri, USA. His current research focuses on sensing and imaging in complex media, with an emphasis on deep tissue imaging based on wavefront engineering.

Cheng Ma’s research interests center on biophotonics that integrate modern optics, electronics and signal processing. 


 

基于时间反演的深度组织光聚焦

报告提要:

生物光学成像(包括共焦显微镜,双光子显微镜,以及光学相干断层扫描等)为我们提供了丰富的生物活体组织信息,但由于生物组织中微观的折射率不均匀性导致的强烈光散射等原因,成像深度通常限制在皮肤表面以下1毫米:此时光子已平均经过10次以上的散射,其传播因此变得完全随机。当前,通过光学时间反演实现对散射的有效抑制“波前工程”正成为一个崭新的研究领域 [1],正以非常快的速度发展,并将对于生物光子学的研究直到临床应用产生革命性的影响。本报告将主要介绍我们研究组在这个领域的原创性成果,包括利用介质自发运动进行的无创、非接触式跟踪/成像技术 [2],以及散射介质内超声导引的快速光聚焦 [3] 等等。我们相信,这些原理和技术将对深度组织的活体成像和治疗产生深远的影响。最后,本报告将讨论这一工作目前面临的主要问题及其解决思路。

参考文献:

[1]   P. Mosk, A. Lagendijk, G. Lerosey, and M. Fink, "Controlling waves in space and time for imaging and focusing in complex media," Nature Photonics 6, 283-292 (2012).

[2]   C. Ma, X. Xu, Y. Liu, and L. V. Wang, "Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media," Nature Photonics, doi:10.1038/nphoton. 2014.251 (2014).

[3]   Y. Liu, P. Lai, C. Ma, X. Xu, A. A. Grabar and L. V. Wang, Optical focusing deep inside dynamic scattering media with time-reversed ultrasonically encoded (TRUE) light, Nature Communications, in press.

 

报告人简介:

马骋于2004年在清华大学电子工程系取得学士学位。2012年,他在美国弗吉尼亚理工大学获得电气工程博士学位,博士期间他的主攻方向是光学传感器以及传感系统,包括基于光谱干涉,吸收光谱,以及光机谐振的传感器系统。从2012年至今,他在美国华盛顿大学(圣路易斯)生物医学工程系进行博士后研究,目前的研究方向是复杂介质中的传感和成像问题,研究重点是基于波前工程的深度组织活体成像。

马骋的研究兴趣主要集中在生物光子学,并着重强调对于当代光子学,电子学以及信号处理技术的融合和利用。