Zhao Tianrui, Deng Liang, Wang Wen, Elson Daniel S, Su Lei
Opt Express. 2018 Aug 6;26(16):20368-20378. doi: 10.1364/OE.26.020368.
In this paper, we present a Bayes' theorem-based high-speed algorithm, to measure the binary transmission matrix of a multimode fiber using a digital micromirror device, in a reference-less multimode fiber imaging system. Based on conditional probability, we define a preset threshold to locate those digital-micromirror-device pixels that can be switched 'ON' to form a focused spot at the output. This leads to a binary transmission matrix consisting of '0' and '1' elements. High-enhancement-factor light focusing and raster-scanning at the distal end of the fiber are demonstrated experimentally. The key advantage of our algorithm is its capability for fast calibration of a MMF to form a tightly focused spot. In our experiment, for 5000 input-output pairs, we only need 0.26 s to calibrate one row of the transmission matrix to achieve a focused spot with an enhancement factor of 28. This is more than 10 times faster than the prVBEM algorithm. The proposed Bayes' theorem-based binary algorithm can be applied not only in multimode optical fiber focusing but also to other disordered media. Particularly, it will be valuable in fast multimode fiber calibration for endoscopic imaging.
在本文中，我们提出了一种基于贝叶斯定理的高速算法，用于在无参考多模光纤成像系统中，使用数字微镜器件测量多模光纤的二元传输矩阵。基于条件概率，我们定义了一个预设阈值，以定位那些可以“开启”的数字微镜器件像素，从而在输出端形成一个聚焦光斑。这就产生了一个由“0”和“1”元素组成的二元传输矩阵。实验证明了在光纤远端实现了高增强因子的光聚焦和光栅扫描。我们算法的关键优势在于其能够快速校准多模光纤以形成紧密聚焦光斑。在我们的实验中，对于5000个输入 - 输出对，我们仅需0.26秒就能校准传输矩阵的一行，以实现增强因子为28的聚焦光斑。这比prVBEM算法快10倍以上。所提出的基于贝叶斯定理的二元算法不仅可以应用于多模光纤聚焦，还可以应用于其他无序介质。特别是，它在用于内窥镜成像的快速多模光纤校准中将具有重要价值。
