Focusing light inside scattering media with magnetic-particle-guided wavefront shaping.
Focusing light inside scattering media with magnetic-particle-guided wavefront shaping.
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DOI：
10.1364/optica.4.001337
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发表时间：
2017-11-20
期刊：
影响因子：
10.4
通讯作者：
Yang C
中科院分区：
文献类型：
--
作者：
Ruan H;Haber T;Liu Y;Brake J;Kim J;Berlin JM;Yang C
光学散射传统上限制了将光聚焦在散射介质（诸如生物组织）内的能力。最近开发的波前整形技术有望克服这一限制，通过定制的光学波前相长干涉在散射介质内的目标位置深处。为了找到这样的波前解，需要一个“引导星”机制来识别目标位置。然而，开发实用的导航星是具有挑战性的，特别是在生物组织中，这阻碍了波前成形技术的转化。在这里，我们展示了一个导星机制，依赖于小颗粒的磁调制。这种guidestar方法的光学调制效率为29%，能够在生物组织内实现微米级聚焦，峰值强度与背景比（PBR）为140;这两个数字都比超声guidestar（一种流行的guidestar方法）高出一个数量级。我们还证明了光可以聚焦在标记有磁性颗粒的细胞上，并通过磁性控制颗粒的位置到达不同的目标位置。由于磁场即使穿过颅骨等骨骼结构也具有很大的穿透深度，因此这种光学聚焦方法对于深层组织应用具有很大的希望，例如神经元的光遗传学调制，靶向光基治疗和成像。
Optical scattering has traditionally limited the ability to focus light inside scattering media such as biological tissue. Recently developed wavefront shaping techniques promise to overcome this limit by tailoring an optical wavefront to constructively interfere at a target location deep inside scattering media. To find such a wavefront solution, a “guide-star” mechanism is required to identify the target location. However, developing guidestars of practical usefulness is challenging, especially in biological tissue, which hinders the translation of wavefront shaping techniques. Here, we demonstrate a guidestar mechanism that relies on magnetic modulation of small particles. This guidestar method features an optical modulation efficiency of 29% and enables micrometer-scale focusing inside biological tissue with a peak intensity-to-background ratio (PBR) of 140; both numbers are one order of magnitude higher than those achieved with the ultrasound guidestar, a popular guidestar method. We also demonstrate that light can be focused on cells labeled with magnetic particles, and to different target locations by magnetically controlling the position of a particle. Since magnetic fields have a large penetration depth even through bone structures like the skull, this optical focusing method holds great promise for deep-tissue applications such as optogenetic modulation of neurons, targeted light-based therapy, and imaging.