Wang Daifa, Zhou Edward Haojiang, Brake Joshua, Ruan Haowen, Jang Mooseok, Yang Changhuei
Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, California 91125, USA ; Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, California 91125, USA.
Optica. 2015 Aug 20;2(8):728-735. doi: 10.1364/OPTICA.2.000728.
Digital optical phase conjugation (DOPC) is a new technique employed in wavefront shaping and phase conjugation for focusing light through or within scattering media such as biological tissues. DOPC is particularly attractive as it intrinsically achieves a high fluence reflectivity in comparison to nonlinear optical approaches. However, the slow refresh rate of liquid crystal spatial light modulators and limitations imposed by computer data transfer speeds have thus far made it difficult for DOPC to achieve a playback latency of shorter than ~200 ms and, therefore, prevented DOPC from being practically applied to thick living samples. In this paper, we report a novel DOPC system that is capable of 5.3 ms playback latency. This speed improvement of almost 2 orders of magnitude is achieved by using a digital micromirror device, field programmable gate array (FPGA) processing, and a single-shot binary phase retrieval technique. With this system, we are able to focus through 2.3 mm living mouse skin with blood flowing through it (decorrelation time ~30 ms) and demonstrate that the focus can be maintained indefinitely-an important technological milestone that has not been previously reported, to the best of our knowledge.
数字光学相位共轭(DOPC)是一种用于波前整形和相位共轭的新技术,用于通过生物组织等散射介质或在其中聚焦光。与非线性光学方法相比,DOPC特别具有吸引力,因为它本质上能实现高能量反射率。然而,液晶空间光调制器的刷新率较慢以及计算机数据传输速度的限制,使得DOPC至今难以实现短于约200毫秒的回放延迟,因此阻碍了DOPC实际应用于较厚的活体样本。在本文中,我们报告了一种新型DOPC系统,其能够实现5.3毫秒的回放延迟。通过使用数字微镜器件、现场可编程门阵列(FPGA)处理和单次二进制相位检索技术,实现了近两个数量级的速度提升。借助该系统,我们能够透过有血液流动的2.3毫米厚的活体小鼠皮肤进行聚焦(去相关时间约30毫秒),并证明该焦点可以无限期保持——据我们所知,这是一个此前未被报道过的重要技术里程碑。