Light is the tool of the 21st century. New photosensitive tools offer the possibility to monitor and control neuronal activity from the sub-cellular to the integrative level. This ongoing revolution has motivated the development of new optical methods for light stimulation. Among them, it has been recently demonstrated that a promising approach is based on the use of wavefront shaping to generate optically confined extended excitation patterns. This was achieved by combining the technique of temporal focusing with different approaches for lateral light shaping including low numerical aperture Gaussian beams, holographic beams and beams created with the generalized phase contrast mthod. What is needed now is a precise characterization of the effect of scattering on hese different methods in order to extend their use for in depth excitation. Here we present a theoretical and experimental study on the effect of scattering on the propagation of wavefront shaped beams. Results from fixed and acute cortical slices show that temporally focused spatial patterns are extremely robust against the effects of scattering and this permits their three-dimensional confinement for depths up to 550 μm.
Plum pudding random medium model of biological tissue toward remote microscopy from spectroscopic light scattering
生物组织具有复杂的结构，并表现出丰富的光谱行为。到目前为止，有\emph{no}组织模型能够解释观察到的组织光散射光谱及其各向异性。在这里，我们提出，\emph{for the first time}，葡萄干布丁随机介质（PPRM）模型的生物组织，简洁地描述了组织作为一个叠加的独特的散射结构（李子）嵌入在一个分形连续介质的背景折射率波动（布丁）。PPRM忠实地再现了组织光散射的波长依赖性，并将各向异性中的“异常”趋势归因于李子，将减少的散射系数的幂律依赖性归因于分形散射布丁。最重要的是，PPRM开辟了一个新的场所，量化的组织结构和微观结构平均从宏观探测的散装与散射光单独没有组织切除。我们通过可视化非接触式光谱测量推导出的乳腺组织（脂肪、腺体、纤维囊性、纤维腺瘤和导管癌）的精细微观结构变化来证明这一潜力。
Sub-40 nm resolution deep tissue imaging by image scanning emission saturation nanoscopy
School of Physics, Beihang University（北京航空航天大学物理学院）；School of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Technology Sydney（悉尼科技大学工程与信息科技学院生物医学工程系）；School of Life Sciences, Peking University（北京大学生命科学学院）
Evaluation of electric and magnetic fields distribution and SAR induced in 3D models of water containers by radiofrequency radiation using FDTD and FEM simulation techniques
