为解决光纤干涉仪输出条纹可见度受单模光纤双折射效应引起的偏振衰落影响,提出一种消除偏振衰落的简单方法,该方法可同时实现光纤干涉仪传感器的空间点探测。设计一种内置旋转角度为45°的法拉第旋光器的传感探头,将其与旋转角度为45°的法拉第旋转镜分别加在Michelson光纤干涉仪的两端。对干涉仪系统进行了理论计算分析,在外界环境变化和偏振控制器改变条件下进行干涉仪可见度测量实验。结果表明:该方法在对外界进行点探测的同时能够有效克服光纤干涉仪的偏振衰落,得到了变化小于0.9% 的干涉稳定度。

In this study, we developed a novel photoacoustic imaging technique based on poly (ethyleneglycol)-coated (PEGylated) gold nanorods (PEG-GNRs) (as the contrast agent) combined with traditional Chinese medicine (TCM) acupuncture (as the auxiliary method) for quantitatively monitoring contrast enhancement in the vasculature of a mouse brain in vivo. This study takes advantage of the strong near-infrared absorption (peak at ~700 nm) of GNRs and the ability to adjust the hemodynamics of acupuncture. Experimental results show that photoacoustic tomography (PAT) successfully reveals the optical absorption variation of the vasculature of the mouse brain in response to intravenous administration of GNRs and acupuncture at the Zusanli acupoint (ST36) both individually and combined. The quantitative measurement of contrast enhancement indicates that the composite contrast agents (integration of acupuncture and GNRs) would greatly enhance the photoacoustic imaging contrast. The quantitative results also have the potential to estimate the local concentration of GNRs and even the real-time effects of acupuncture.

研究了基于3×3耦合器的光纤马赫-曾德尔干涉仪的三路输出干涉信号的特点,针对相位衰落问题,提出了一种根据所得的正交信号来判断反馈正负性的方案。实验通过LabVIEW软件来实现正交信号的获得及反馈输出信号的处理。测量和分析得到了直接输出反馈信号时会出现干涉信号短暂偏离稳定点的情况,整个过程的时间约为35 ms,而采用所提反馈正负判断方案后,相位稳定所需时间约为18 ms。通过一个光纤准直聚焦系统把光入射到被测物体表面并接收反射光,探测到了与输入信号频率一致的1.5 MHz的高频振动信号。验证了正负反馈判断方案及设计干涉系统的可行性和有效性。

Tongue cancer is an increasingly common disease with high morbidity. Besides clinical observation, biomedical imaging techniques have been investigated for early detection of tongue cancer. In this paper, we proposed a co-registered dual-modality photoacoustic (PA) and ultrasound imaging technique to simultaneously map the functional and structural information of human tongue, which has the potential to detect and diagnose tongue cancer in early stage. The imaging probe comprises a 20-MHz side-view focused transducer for ultrasound imaging and PA detection, a light path constructed by a multimode optical fiber, and a prism for PA illumination. Phantom experiments were conducted to evaluate the performance of the system including penetration depth, spatial resolution and signal-to-noise ratio. In vivo imaging of animal tumor and human tongue was carried out to show the feasibility of the proposed technique to detect tumor lesions in human tongue. The results of phantom and in vivo experiments suggest that the proposed technique has the potential to detect the early-stage cancer lesions in human tongue.

Here, we report a new method using combined magnetic resonance (MR)–Photoacoustic (PA)– Thermoacoustic (TA) imaging techniques, and demonstrate its unique ability for in vivo cancer detection using tumor-bearing mice. Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property distributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging (MRI) unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice. Three plastic tubes filled with soybean sauce were used as fiducial markers for the co-registration of MR, PA and TA images. The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues. In particular, some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images. These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier. This combined MR–PA–TA-imaging strategy has the potential to offer a clinically useful triplemodality tool for accurate cancer detection and for intraoperative surgical navigation.

文中提出了一种基于遗传算法并考虑空域距离关系来设计细胞神经网络模板参数并实现森林红外图像动物边缘检测的算法。仿真结果表明，该算法与其他的森林红外图像边缘检测算法相比，能很好地抑制噪声对边缘检测的干扰，保留边缘信息，同时能较好地检测出红外图像动物的边缘，检测精度高，具有良好的应用前景。

为避免经典固定模型集合中多模型算法造成的模型间竞争并减小计算量, 基于有向图切换的变结构方法, 建立有向图切换规则和较完备的模型集合.通过模糊逻辑推理得到模型集合中各模型的匹配度, 以此代替传统多模型算法中的模式概率来计算,降低了计算的复杂度.采用核粒子滤波克服了标准粒子滤波没有考虑到的量测信息问题, 即粒子能够通过核密度估计后朝着状态的后验概率密度的模型移动, 使真实和估计模型之间的均方误差最小.仿真结果表明, 基于模糊理论的变结构核粒子滤波算法能较大地提高跟踪准确度和减少计算量.

严格耦合波分析(RCWA)法在测量二维周期光栅的关键尺寸(CD)和获得其剖面结构中有着较为广泛的应用。在这个应用过程中需要对二维光栅周期单元的相对介电常数分布表达式进行傅里叶级数展开，而在以往的研究中只提出了几种规则光栅的傅里叶系数求解公式，从而使得能够应用RCWA方法进行衍射分析的光栅在形状方面受到了一定的限制。针对这一局限，运用矩形网格细分的方法得到了计算二维周期光栅的相对介电常数傅里叶系数的通用公式，它能够对任意形状的二维周期光栅相对介电常数分布进行傅里叶级数展开，并运用于衍射问题的RCWA方法分析之中。

在分析频偏对信号星座图影响的基础上，提出了一种基于盲源分离的载波残余频偏与相偏的估计方法。首先对接收信号进行中心化和白化的预处理，且用以随机数初始化的分离矩阵对接收的数据点进行实时分离处理；然后结合随机梯度算法对分离矩阵、混合矩阵以及全局矩阵进行估计，并用基于全局矩阵估计的PI值对变步长进行更新；最后根据分离矩阵中各元素间的关系估计出残余频偏信号的相位变化轨迹，即可进一步由相邻相位突跳点间的间隔数估计出载波频偏的大小。仿真结果表明，该方法能有效地估计出接收信号的残余频偏与固定相偏值。

椭偏仪是薄膜测量的重要工具。从模拟和实验两方面，描述一种新颖的单波长椭偏仪的校准方法。该方法的基本思路是：如果被测样品的相关信息(折射率n,吸收系数k,厚度d)已知，则可以通过测量光强变化的傅里叶系数，采用最小二乘法原理反演出此时椭偏系统的信息（即校准参数，包括起偏器方位角P，检偏器方位角A，波片起始旋转角Cs，波片位相延迟δ，系统入射角θ0）。利用校准得到的系统参数和测量未知样品得到的光强傅里叶系数，求得未知样品的厚度。该方法具有操作简单、节约成本等优点。分别针对2~6个样品尝试了校准，对该校准方法做了模拟分析。将该方法用于实际测量，考证校准后的测量效果，并做了误差分析,最大误差为0.26 nm。