Yang Jiamiao, He Qiaozhi, Liu Linxian, Qu Yuan, Shao Rongjun, Song Bowen, Zhao Yanyu
Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, 200240, Shanghai, China.
Shanghai Center for Brain Science and Brain-Inspired Technology, 200031, Shanghai, China.
Light Sci Appl. 2021 Jul 20;10(1):149. doi: 10.1038/s41377-021-00591-w.
Speed and enhancement are the two most important metrics for anti-scattering light focusing by wavefront shaping (WS), which requires a spatial light modulator with a large number of modulation modes and a fast speed of response. Among the commercial modulators, the digital-micromirror device (DMD) is the sole solution providing millions of modulation modes and a pattern rate higher than 20 kHz. Thus, it has the potential to accelerate the process of anti-scattering light focusing with a high enhancement. Nevertheless, modulating light in a binary mode by the DMD restricts both the speed and enhancement seriously. Here, we propose a multi-pixel encoded DMD-based WS method by combining multiple micromirrors into a single modulation unit to overcome the drawbacks of binary modulation. In addition, to efficiently optimize the wavefront, we adopted separable natural evolution strategies (SNES), which could carry out a global search against a noisy environment. Compared with the state-of-the-art DMD-based WS method, the proposed method increased the speed of optimization and enhancement of focus by a factor of 179 and 16, respectively. In our demonstration, we achieved 10 foci with homogeneous brightness at a high speed and formed W- and S-shape patterns against the scattering medium. The experimental results suggest that the proposed method will pave a new avenue for WS in the applications of biomedical imaging, photon therapy, optogenetics, dynamic holographic display, etc.
速度和增强效果是通过波前整形（WS）进行抗散射光聚焦的两个最重要指标，这需要具有大量调制模式和快速响应速度的空间光调制器。在商用调制器中，数字微镜器件（DMD）是唯一能提供数百万种调制模式且图案速率高于20 kHz的解决方案。因此，它有潜力加速高增强效果的抗散射光聚焦过程。然而，DMD以二进制模式调制光严重限制了速度和增强效果。在此，我们提出一种基于多像素编码DMD的WS方法，通过将多个微镜组合成单个调制单元来克服二进制调制的缺点。此外，为了有效优化波前，我们采用了可分离自然进化策略（SNES），它可以在有噪声的环境中进行全局搜索。与基于DMD的最新WS方法相比，所提出的方法分别将优化速度和聚焦增强效果提高了179倍和16倍。在我们的演示中，我们高速实现了10个亮度均匀的焦点，并针对散射介质形成了W形和S形图案。实验结果表明，所提出的方法将为WS在生物医学成像、光子治疗、光遗传学、动态全息显示等应用中开辟一条新途径。
