A communication channel should be built to transmit information from one place to another. Imaging is 2 or higher dimensional information communication. Conventionally, an imaging channel comprises a lens with free space at its both sides, whose transfer function is usually known and hence the response of the imaging channel can be well defined. Replacing the lens with a thin scattering medium, the image can still be extracted from the detected optical field, suggesting that the scattering medium retains or reconstructs not only energy but also information transmission channels. Aided by deep learning, we find that unlike the lens system, there are different channels in a scattering medium: the same scattering medium can construct different channels to match the manners of source coding. Moreover, it is found that without a valid channel, the convolution law for a spatial shift-invariant system (the output is the convolution of the point spread function and the input object) is broken, and in this scenario, information cannot be transmitted onto the detection plane. Therefore, valid channels are essential to transmit information through even a spatial shift-invariant system. These findings may intrigue new adventures in imaging through scattering media and reevaluation of the known spatial shift-invariance in various areas.

High-resolution optical imaging through or within thick scattering media is a long sought after yet unreached goal. In the past decade, the thriving technique developments in wavefront measurement and manipulation do not significantly push the boundary forward. The optical diffusion limit is still a ceiling. In this work, we propose that a scattering medium can be conceptualized as an assembly of randomly packed pinhole cameras and the corresponding speckle pattern as a superposition of randomly shifted pinhole images. The concept is demonstrated through both simulation and experiments, confirming the new perspective to interpret the mechanism of information transmission through scattering media under incoherent illumination. We also analyze the efficiency of single-pinhole and dual-pinhole channels. While in infancy, the proposed method reveals a new perspective to understand imaging and information transmission through scattering media.

利用相位恢复算法可以从光纤近端的光强分布求解光纤远端的场强分布。光纤的响应可以用传输矩阵描述。实验上则是在不同的输入情况下对输出端的光强分布进行足够数量的采样来测量传输矩阵。显然，采样点的位置分布，包括采样点数目和间隔，影响着传输矩阵的测量，而相位恢复算法的精度和效率与传输矩阵有关。文中提出采样间隔应该大于出射散斑大小，以满足传输矩阵不同行的统计独立性，在保证图像重建质量的条件下减少采样点数，提高重建效率。实验结果表明，当采样间隔小于散斑大小时，相同的图像重建质量下，随着采样间隔的增大，光场重建所需的采样点数量明显下降。当采样间隔大于散斑时，所需的采样点数量变化缓慢，约为输入图像像素数量的3.5倍。采样间隔固定时，随着采样点数的增加，相位恢复算法消耗的时间先减小后增大，因此存在一个最佳的采样间隔与采样点数。

睡眠障碍是临床中的常见多发病，睡眠障碍易诱发和加重认知障碍疾病，损害海马依赖的学习记忆功能。光疗是一种改善睡眠的有效方法，鉴于此，本课题组研究了光疗对睡眠剥夺小鼠炎症反应、氧化应激反应及BDNF-TrkB信号通路的影响，探索光疗对睡眠剥夺小鼠学习记忆的影响。通过旋转圆筒法建立睡眠剥夺模型，小鼠随机被分为对照组、睡眠剥夺组、光疗组(468 nm，光照强度分别为100，300，900 lx)。光疗组边剥夺边治疗，每天早晚进行光照30 min，于剥夺3 d后对各组小鼠进行水迷宫实验和旷场实验，采用ELISA法检测小鼠血浆和海马组织中TNF-α、SOD、5-HT因子的表达量，采用RT-PCR法检测小鼠BDNF、TrkB和Akt中的mRNA表达量。结果显示：与对照组相比，睡眠剥夺导致小鼠体重下降，游泳潜伏期增长，促进了炎性因子TNF-α的表达，降低了SOD活性和5-HT的表达，并降低了BDNF、TrkB和Akt中的mRNA表达；与睡眠剥夺组相比，光疗组小鼠的游泳潜伏期缩短，平台交叉次数增多，TNF-α表达下降，SOD和5-HT表达呈上升趋势，焦虑样行为减轻，BDNF、TrkB与Akt中的mRNA表达升高；300 lx光照剂量的效果较为显著。光疗可以修复睡眠剥夺引起的氧化应激损伤，调节炎症反应，促进BDNF表达，代偿相对较短时间的睡眠剥夺，保护自身的认知能力，缓解睡眠剥夺引起的学习记忆缺陷。

日常生活中常常会出现各种散射介质,如毛玻璃、生物软组织和云雾等。毛玻璃一般可看作是没有厚度的面散射介质,即随机相位屏,而鸡胸肉等生物软组织是厚度不可忽略的体散射介质。光在鸡胸肉等体散射介质内的传播过程复杂,受厚度、各向异性因子等因素的影响。在实际研究中,科研人员经常选用毛玻璃作为散射介质,并倾向于把相关结论直接推广到鸡胸肉等体散射介质上。从能量分布出发,对比分析了毛玻璃和体散射介质在成像和散射强度分布上的差异,提出了一种积分发散角测量方法,探究了二者散斑分布近似等效的条件。

创面愈合延迟是最具挑战性的糖尿病临床并发症之一，其与活性氧（ROS）的过量生成有关。光生物调节作用（PBM）可以从多方面促进创面愈合，可作为糖尿病患者创面延迟愈合的一种治疗方法。本文研究了PBM对高糖培养的人胚胎皮肤成纤维细胞（CCC-ESFs）活性氧稳态的影响，探讨了PBM对改善细胞氧化应激损伤的作用。首先体外培养CCC-ESFs，细胞被随机分为对照组（正常培养基和高糖培养基）和808 nm激光照射组（功率密度分别为10，20，40 mW/cm²，能量密度分别为1.5，3，6，12 J/cm²），对照组不照光。高糖造模48 h后进行激光照射，随后分别检测细胞的增殖活力、ROS含量、总超氧化物歧化酶含量、总抗氧化能力、线粒体膜电位和相关细胞因子表达量。结果表明：高糖环境降低了细胞的增殖活力，ROS含量显著增多，抗氧化能力下降，细胞凋亡增多；采用808 nm激光照射后，细胞的增殖效应没有得到明显改善，但细胞的ROS含量下降，抗氧化酶表达量出现上升趋势，促炎细胞因子表达量降低。这些结果表明，PBM可以修复高糖环境下产生的氧化应激损伤，调节炎症反应，促进创伤愈合。

为了减少多个星敏感器地面热漂移标定时受到不同安装平台的位置误差影响,采取一种多星敏感器地面热漂移标定位置误差检测方法, 进行了理论分析和实验验证, 取得了-25℃~60℃真空状态下系统中基准方棱镜变形的位置偏移量数据, 并进行了标定位置误差精度分析。结果表明, 多星敏感器位置绕各轴产生的最大偏移量分别为-39.341″/℃,-0.060″/℃,-24.137″/℃, 通过建立误差检测模型对位置误差进行计算, 将其从姿态测量结果的偏移量中剔除后获得更准确的星敏感器姿态测量四元数, 剔除位置误差后的系统精度至少提高了11%。该研究在提高星敏感器热漂移标定精度方面具有很好的应用前景。

提出一种基于误差解耦的星敏感器热漂移标定系统。根据标定原理和星等模拟要求,设计自准直光学标定系统和误差解耦光路。根据共光路特性,由自准直仪和CCD获得星敏感器安装误差和热变形与安装变形形成的耦合误差,将安装变形误差从耦合误差中剔除后获得准确的星敏感器姿态转移四元数。仿真试验结果表明,温度范围在-25~60 ℃环境下,星敏感器标定时绕各轴产生的最大变化误差分别为0.2638,0.1317,0.0472 (″)/℃,与理想结果误差控制在0.02 (″)/℃的范围内,这为减少星敏感器标定中产生的耦合误差和提高热漂移标定精度提供一种新的思路和方法。

We observed a phenomenon that different scattering components have different decorrelation time. Based on decorrelation time difference, we proposed a method to image an object hidden behind a turbid medium in a reflection mode. In order to suppress the big disturbance caused by reflection and back scattering, two frames of speckles are recorded in sequence, and their difference is used for image reconstruction. Our method is immune to both medium motions and object movements.