Kim Dong-Young, Jeong Seungwon, Jang Mooseok, Lee Ye-Ryoung, Choi Wonshik
Opt Express. 2020 Mar 2;28(5):7382-7391. doi: 10.1364/OE.385557.
Light waves propagating through complex biological tissues are spatially spread by multiple light scattering, and this spread limits the working depth in optical bioimaging, phototherapy, and optogenetics. Here, we propose the iterative phase conjugation of time-gated backscattered waves for enhancing the light energy delivered to a target object embedded in a scattering medium. We demonstrate the enhancement of light energy delivered to a target object hidden behind a 200-µm-thick mouse skull by more than ten times in comparison with the initial random input. The maximum enhancement was reached in only 10 iterations, more than a hundred times smaller than existing methods based on either a time-gated reflection matrix or iterative feedback optimization of the time-gated reflection intensity. Consequently, the proposed method is less sensitive to sample perturbations. Furthermore, the number of images required for optimization remained almost unchanged with an increase in the illumination area, unlike existing methods, where the convergence time scales with the illumination area. The proposed method provides high operation speed over a wide illumination area, which can facilitate the use of wavefront shaping in practical applications.
在复杂生物组织中传播的光波会因多次光散射而在空间上扩散，这种扩散限制了光学生物成像、光疗和光遗传学中的工作深度。在此，我们提出对时间选通后向散射波进行迭代相位共轭，以增强传递到嵌入散射介质中的目标物体的光能。我们证明，与初始随机输入相比，传递到隐藏在200微米厚小鼠头骨后的目标物体的光能增强了十多倍。仅在10次迭代中就达到了最大增强效果，这比基于时间选通反射矩阵或时间选通反射强度的迭代反馈优化的现有方法小一百多倍。因此，所提出的方法对样本扰动不太敏感。此外，与现有方法不同，现有方法的收敛时间与照明面积成比例，而所提出的方法优化所需的图像数量几乎不会随着照明面积的增加而变化。所提出的方法在宽照明区域上提供了高运算速度，这有助于在实际应用中使用波前整形。
