High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping.
High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping.
复制标题
DOI：
10.1063/1.5009113
复制
发表时间：
2017-11
影响因子：
4
通讯作者：
A. Hemphill;Yuecheng Shen;Yan Liu;Lihong V. Wang
中科院分区：
文献类型：
--
作者：
A. Hemphill;Yuecheng Shen;Yan Liu;Lihong V. Wang
在生物学应用中，光学聚焦受到光的漫射的限制，这阻止了在软组织中大于1.01 mm的深度处的聚焦。波前成形通过补偿由散射引起的相位失真来扩展深度，并且因此允许通过使用相长干涉来使光聚焦通过生物组织超过光学扩散极限。然而，由于生理运动，组织中的光散射仅在短暂的散斑相关时间内是确定性的。在体内组织中，该散斑相关时间为毫秒量级，因此波前必须在该短暂的时间段内被优化。数字波前整形的速度通常受到测量和显示最佳相位图案所需的相对较长时间的限制。这种限制源于相机、数据传输和处理以及空间光调制器的低速。虽然二进制相位调制只需要两个图像的相位测量最近已经报道，大多数技术需要至少三个帧的全相位测量。本文提出了一种基于离轴全息术的全相位数字光学相位共轭方法，用于散射介质中的单次光学聚焦。通过使用离轴全息术结合基于图形处理单元的处理，我们利用单次全相位测量，同时使用并行计算来快速重建相位图。利用该系统，我们可以聚焦光通过散射介质，系统延迟约为9 ms，在体内散斑相关时间的数量级上。
In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ∼1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. In in vivo tissue, this speckle correlation time is on the order of milliseconds, and so the wavefront must be optimized within this brief period. The speed of digital wavefront shaping has typically been limited by the relatively long time required to measure and display the optimal phase pattern. This limitation stems from the low speeds of cameras, data transfer and processing, and spatial light modulators. While binary-phase modulation requiring only two images for the phase measurement has recently been reported, most techniques require at least three frames for the full-phase measurement. Here, we present a full-phase digital optical phase conjugation method based on off-axis holography for single-shot optical focusing through scattering media. By using off-axis holography in conjunction with graphics processing unit based processing, we take advantage of the single-shot full-phase measurement while using parallel computation to quickly reconstruct the phase map. With this system, we can focus light through scattering media with a system latency of approximately 9 ms, on the order of the in vivo speckle correlation time.