【摘 要】
：
In the characterization of elastic properties of tissue using dynamic optical coherence elastography, shear/surface waves are propagated and tracked in order to estimate speed and Young's modulus. However, for dispersive tissues, the displacement pulse i
【机 构】
：
DepartmentofElectricalandComputerEngineering,UniversityofRochester,Rochester,NewYork14627,USATheInst
【出 处】
：
JournalofInnovativeOpticalHealthSciences
论文部分内容阅读
In the characterization of elastic properties of tissue using dynamic optical coherence elastography, shear/surface waves are propagated and tracked in order to estimate speed and Young's modulus. However, for dispersive tissues, the displacement pulse is highly damped and distorted during propagation, diminishing the effectiveness of peak tracking approaches, and leading to biased estimates of wave speed. Further, plane wave propagation is sometimes assumed, which contributes to estimation errors. Therefore, we invert a wave propagation model that incorporates propagation, decay, and distortion of pulses in a dispersive media in order to accurately estimate its elastic and viscous components. The model uses a general first-order approximation of dispersion, avoiding the use of any particular rheological model of tissue. Experiments are conducted in elastic and viscoelastic tissue-mimicking phantoms by producing a Gaussian push using acoustic radiation force excitation and measuring the wave propagation using a Fourier domain optical coherence tomography system. Results confirmed the effectiveness of the inversion method in estimating viscoelastic parameters in both the viscoelastic and elastic phantoms when compared to mechanical measurements. Finally, the viscoelastic characterization of a fresh porcine cornea was conducted. Preliminary results validate this approach when compared to other methods.
其他文献
本文论述了35mm电影大孔径变焦距物镜的设计特点,提出了消象散中间固定组的结构。最后给出了具有中间固定组的新型变焦距物镜实例。它的焦距范围为25～85 mm,相对孔径为1/1.4,视场角为57°～18°。
研究了水、氯化镁、硫酸镁等无机盐水溶液及乙醇、乙腈等有机溶剂的光声温度效应。探讨了温度变化、液体分子结构弛豫和溶液特性改变对光声信号强度和峰形的影响。
设计了一种基于异质结构的低串扰3-LP模12芯光纤,纤芯采用异质无沟槽辅助的环形折射率分布,结构简单且能增大纤芯的有效模场面积。利用COMSOL软件分析了异质纤芯的芯间串扰、有效模场面积等性能,结果表明,异质纤芯LP01,LP11,LP21模的芯间串扰分别低于-0.78,-0.66,-0.4 dB/km,有效模场面积分别为150,166,200 μm 2。使用方点阵型纤芯排布方式,可实现包层直径约为213.8 μm、相对纤芯复用因子为26.9的低串扰3-LP模12芯光纤设计,为通信容量的升级扩容提供器件支
研究了强激光长程空气传输过程中主光束能量损耗与光束质量退化效应。使用1053 nm单波长、线偏振、脉宽3 ns平顶激光脉冲于空气环境中长距离传输，当入射光强与传输距离乘积大于13.7 TW/cm时，传输末端测得的光束光谱分布中出现了多种散射光频率成分，各散射光成分和1053 nm主激光间的频率差与氮气分子不同转动能级间跃迁频率一致，证明氮气分子的受激转动拉曼散射效应已建立。受激转动拉曼散射过程中，入射光束功率密度微弱变化所产生的散射光能量变化剧烈。入射光强与传输距离乘积大于17 TW/cm时，传输末端光束
High power laser diodes (LDs) with a lasing wavelength between 700 and 780 nm have great potential in various medical uses. Here, we report our recent efforts in developing an InGaAsP/AlGaInP-based commercial high power edge-emitting LD, which has 755 nm
SnO2 thin films with good orientation are prepared on a glass substrate by radio frequence (RF) reactive sputtering. The phases of the thin films before and after annealing are analyzed by X-ray diffraction (XRD) spectroscopy, and the surface morphologies
椭偏仪实现高精度测量的关键在于模型值的精准标定,而随机误差是影响标定精度的重要因素。从椭偏仪随机误差的产生原因入手,针对零阶噪声受限、一阶噪声受限、二阶噪声受限三种可能存在的系统,对测量结果随机误差进行了数值估计。为了降低测量结果的随机误差,采用枚举法和遗传算法,得到了三种系统下的最佳配置。数值分析和实验结果表明,比起常用的配置,最佳配置下的随机误差可以降低1/3以上。本文虽然仅给出三种噪声受限系统的最优配置,但是噪声估计结果和优化方法可以适用于多种噪声模型共同存在的模型。
钙钛矿氧化物NaNbO3是一种极具应用前景的环保型压电材料, 为此科研人员已经对其进行了大量的科学研究。 近年来, NaNbO3高压结构相变的研究有很多, 但是2 GPa附近和12 GPa以上的结构相变序列和晶体结构依旧存在很多争议。 前人利用拉曼光谱研究NaNbO3的结构相变主要关注的是NbO6内部振动引起的结构变化, 没有详细研究低频段的晶格振动对结构相变的影响。 因此, 以体积比为16∶3∶1甲醇、 乙醇和水的混合液作为传压介质, 在准静水压力条件下, 在0~22 GPa压力范围开展NaNbO3粉末
在鬼成像装置的参考光路上安放特定的透射屏,提出了一种新的鬼衍射方案来实现物体相位的定量重建,并给出了对应的理论解释与实验仿真。仿真结果与理论基本吻合,验证了实验方案的正确性与可行性。
High performance optical coating requires excellent uniformity of thin-film. Keeping the surface of evaporation material flat is propitious for the stability of vapor plume, and can improve the uniformity of thin-film. Based on the principle of electron b