650nm光在Intralipid-10%中分布的测量和分析

本文提出一种用光纤测定光在生物组织模型Iitralipid内部光分布的方法并测定了650nm激光在Iitralipid 10%中的分布,该方法与各向同性球形光纤探头探测组织内光分布是一种互补的方法。实验结果揭示了在生物组织模型中不同方向散射光的分布规律,表明了不同的组织光学参数和不同直径的入射光束与光分布之间的关系;采用外推边界条件的漫射方程解拟合前向散射光的测量数据确定了组织模型的散射系数和吸收系数并得到较好的结果,所测量的光学参数与公开发表的结果比较其差别在2 35%以内。     

基于漫反射光谱的组织光学参数测量系统与方法研究

在体组织光学参数测量是生物医学光子学研究重点,不仅为人体成分无创检测、光学成像、光动力疗法等研究提供基础,并且可以快速获取人体光学参数变化,为临床诊断提供依据。研究了利用单一源探距离漫反射光谱在体测量光学参数的测量系统与反构方法。漫反射光谱测量系统由宽谱光源、高分辨光纤光谱仪及光纤探头组成,结构简单,测量方便,可准确快速测量样品漫反射光谱。在光纤探头几何形状基础上,研究了光纤收集及系统传递函数,在此基础上对反构算法进行了校正。光学参数反构算法中正向模型基于Monte Carlo以及神经网络方法,适用光学参数范围大,计算速度快;逆向算法采用主成分分析与非线性建模拟合相结合的方法,可抑制测量噪声影响。在测量系统及反构算法基础上,进行了组织仿体光学参数测量实验,结果表明,利用单一源探距离下漫反射谱,可以较为准确获取吸收系数以及约化散射系数,均方根误差分别达到4.58%以及7.92%。为保证系统测量准确性,测量波长范围应覆盖样品中所含吸收物质吸收峰范围。所研究的在体组织光学参数测量方法为人体成分无创检测及测量条件变化获取提供了基础。     

光学纤维中的散射及其应用

本文介绍光学纤维中的散射理论,给出散射场与光纤参数之间的关系,并举例说明散射过程在光纤折射率分布测量中的应用。     

不同折射率调制的光纤光栅的特性及其应用

介绍了九种不同折射率调制的光纤光栅的折射率分布及其光谱特性,建立了各种光纤光栅的数学模型,并分析了它们的优缺点及其应用特点。给出了各种光纤光栅之间的联系,并指出两种或多种单一折射率分布的光纤光栅的组合形式将是以后的发展趋势。以折射率分布为出发点,深入地讨论了各种光纤光栅的周期、折射率调制深度、中心反射光波长或透射光波长、带宽、反射率等参数与其功能的关系,为实际系统的设计提供了参考。     

有限元法求解任意折射率分布光纤模场分布

 应用有限元方法求解了任意径向非均匀折射率分布园柱对称介质波导中纵向场耦合波动方程定解问题所对应的变分问题,该方法不受弱导或高斯模场分布等限制,可方便地求解光纤中介质波导的模场分布。用此方法研究了带阶跃环的三角型分段折射率分布光纤中归一化模场半径与芯层传输功率比值随光纤不同结构参数的变化规律。     

拉锥光纤中光传输模场的矢量分析

采用二维矢量时域有限差分法(FDTD),考虑了拉锥光纤芯层的折射率分布和光纤芯层直径等参数,详细分析了拉锥光纤的锥度、拉锥后纳米光纤半径等对拉锥光纤中光波模场分布和传输特性的影响。计算结果表明,单模光纤芯层的折射率分布函数对光纤中光传输模场分布影响较小;拉锥光纤锥度越大光波的能量损耗越大;当拉锥后纳米光纤半径逐渐变小时,纳米光纤的光传输模场中心光强先逐渐增强然后又逐渐减小。     

空芯光纤气体传感气室的优化设计

波导式光学吸收腔在气体和液体浓度测量等领域有广泛的应用前景。空芯光纤作为光学吸收腔具有很多优点。空芯光纤的参数与传感系统的性能有直接的关系。提出了一种能同时考虑空芯光纤的损耗和系统信噪比的数学模型。从理论上分析了光纤的长度、内径、目标气体浓度以及输入光场能量分布等因素对传感系统信号输出强度和灵敏度的影响。给出的最优化参数为提高系统灵敏度和补偿系统误差提供了参考。     

应用耦合模理论研究光在圆对称双包层光纤中的传输(英文)

为了深入理解双包层光纤的光场传输特性,应用耦合模理论将双包层光纤等效为相互耦合的单模光纤和环形芯光纤,研究了圆对称的双包层光纤的光场传输.通过计算单模光纤LP01模和环形芯光纤导模的耦合系数发现了环形芯光纤LP0n模的耦合系数远大于其它导模的耦合系数,且LP0n模中的高阶模比低阶模的耦合系数大.据此,应用耦合模理论计算得到了该双包层光纤的光传输特性,计算结果发现光场沿光纤轴向呈近似周期分布,且纤芯中光功率变化的平均周期随波长递增,但平均归一化功率与光纤参数紧的选择有关.     

塑料光纤纤端光场测试结果及分析

对纤端光场进行了理论分析,分别利用塑料光纤和多模光纤作为接收光纤对塑料光纤的出射纤端光场进行了测量,并与理论分析结果进行了比较,给出了合理的调和参数.传输距离较长的塑料光纤由于高阶模的泄漏,纤端光场分布非常接近高斯分布.实验结果表明了理论分析结果和调和参数选择的合理性.     

任意折射率分布单模光纤的色散

本文解决了任意折射率分布单模光纤色散的计算问题.文中引入了光纤的“光学尺寸”这一无量纲参数,并由此导出了新的单模色散公式.色散公式中的各参数分别利用变分-有限元法和Sellmeier系数算出.我们利用依此编制的计算机程序计算了各方次律分布单模光纤在1.3μm和1.55μm这两个低损窗口处的色散曲线,研究了折射率中间凹陷对阶跃单模光纤色散的影响.文中提供的方法不仅可用于计算实际单模光纤的色散,还可用来研究新型光纤,为单模光纤的设计、制造和测量提供重要资料.     

Acoustic properties of a human chest

A cross-spectral method for determining the longitudinal velocity of sound in the tissues of a human chest in vivo is proposed and substantiated. The method is based on the detection of a percussion stroke by two acoustic sensors positioned over opposite parts of a lung. Statistical estimates are obtained for the longitudinal velocity of sound in chest tissues (the middle part of the right lung) from a group of three men (40–47 years old) without any evident lung disorders in the frequency ranges of 80–130, 170–290, and 350–500 Hz. The adequacy of the double-resonance acoustic model of the human respiratory tract, which combines the resonance of the air volume in the human chest and the wave resonances of the bronchial tree as a narrow pipe, is experimentally verified.     

Comparison of optical detection system ,PVDF detection system, and PVDF needle hydrophone for optoacoustic tomography

Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally with that by using thermoelastic waves as a broadband ultrasonic source. For the comparison, an optical stress transducer(OST), a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used.To ensure all of the detection systems interrogated by the same ultrasonic field, a small optical instrument that fixed the generating laser head was constructed. The sensitivity was evaluated by measuring signalto-noise ratios (SNRs) and noise equivalent pressures (NEPs). The PVDF system, with a 4-kPa NEP has a 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broad detection range.     

基于有效衰减系数直接测量的人体光谱特征分析

在活体成分无创测量中,人体组织的漫射光谱之间存在千差万别,即使同一组织的光谱也时刻发生着变化,这是影响活体组织成分测量精度的重要原因。通过漫射光谱实时监测组织的光学特性非常重要。由于漫射光的吸光度光谱沿光源-探测器距离不再呈现线性变化,不同距离下的测量结果不易相互借鉴,因此不宜采用单一距离的漫反射光测量方式。采用双光源-探测器距离的测量方式,通过差分测量获得了组织有效衰减系数,其与测量距离无关,是反映组织吸收、散射的综合光学参数。实验系统采用中心光纤入射,距中心0.6和2.0 mm的两个环状分布的光纤束接收漫反射光,并据此推测出被测组织的有效衰减系数。通过实时监测组织的有效衰减系数,可以监测组织的状态与成分变化信息。采用Intralipid脂肪乳作为组织仿体,考察了其中的葡萄糖浓度、血红蛋白浓度、颗粒密度、温度四个因素变化时在1 000~1 300 nm波段的有效衰减系数光谱,比较了它们的光谱特征。结果表明,有效衰减系数的光谱形状主要由介质的吸收变化决定。其中血红蛋白的有效衰减系数光谱显示出其在1 000~1 200 nm波段吸收显著,1 200~1 300 nm吸收减弱,这与血红蛋白的吸收特征一致;温度的光谱显示出与温度对水吸收光谱影响的光谱形状一致; 葡萄糖与颗粒密度引起的有效衰减系数光谱相似,原因在1 000~1 300 nm波段葡萄糖吸收较弱,其主要影响介质散射特性。最后测量了不同人体的手指、手掌、手背、手臂外侧、手臂内侧的有效衰减系数光谱,比较了部位差异和个体差异。从人体光谱差异上很明显地看到了血红蛋白、散射特性不同引起的光谱差异。综上,提出的有效衰减系数光谱测量方法特别适用于活体组织的成分测量,为实时监测组织的散射、吸收变化提供了一条新途径。     

Determination of optical characteristics of biological tissues by temporal distribution of an ultrashort laser pulse passed through homogeneous scattering layer

The determination of optical characteristics of biological tissues by the temporal distribution of an ultrashort laser pulse passed through a homogeneous scattering layer is considered. Four nonstationary models used to describe passing of laser pulses through a highly scattering medium are compared for the first time. The domains of applicability for the diffusion models are determined. It has been shown that the determination of optical characteristics of highly scattering media by experimental temporal distributions leads to different numerical values depending on the used model. Nevertheless, any of these models can be used because the performed study does not permit one to give preference to any of them. However, in determining optical characteristics of the scattering samples, it is necessary to specify the used model, as well as the conditions under which the initial experimental data (in particular, the thickness of the layer of a studied sample) are obtained.     

应用光纤生物传感器测量肿瘤的自体荧光光谱

光纤生物传感器是现代生物传感技术中的一个非常重要的类别。当前,许多以荧光检测为手段的光纤生物传感器已经商品化了,但几乎都是依靠检测荧光指示剂的光强来获取生物信息,而直接利用生物样品的自体荧光光谱来获取生物信息的光纤传感系统却还未上市。利用自行研发的一套三维荧光光谱光纤传感系统对新鲜的人体乳腺组织切片进行了研究,实验结果表明乳腺癌变组织与正常组织的自体荧光光谱的峰位和峰强比值存在明显区别,这是因为癌变组织的生化成分发生了根本改变。尽管其间的规律还需进一步探索,但可以展望,自体荧光光谱技术与光纤生物传感技术的结合有潜力成为人体恶性肿瘤在线原位诊断的有利工具。     

Noninvasive ultrasound image guided surface wave method for measuring the wave speed and estimating the elasticity of lungs: A feasibility study

Lung diseases, such as acute respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF), are closely associated with altered lung elastic properties. Pulmonary function testing and imaging are routinely performed for evaluating lung diseases. However, lung compliance, a measure of lung elastic properties, is rarely used in clinic, because it is invasive and provides only a global and arguably biased estimate of lung elastic properties. Current ultrasound methods also cannot be used for imaging lungs because ultrasound cannot penetrate the lung tissue. In this paper, an ultrasound image guided and surface wave based method is proposed to measure regional lung surface wave speed and estimate lung elasticity noninvasively. The method described here was not explored before to the best knowledge of the authors. Experiments in an ex vivo pig lung and an in vivo human lung pilot study are reported. The surface wave speed is measured to be 1.83 ± 0.02 m/s at 100 Hz by ultrasound for the ex vivo pig lung at 3 mmHg pressure, which is validated by an optical measurement. An in vivo human lung pilot experiment measures the surface wave speed to be 2.41 ± 0.33 m/s for the 100 Hz sinusoidal wave at total lung capacity (TLC) and 0.99 ± 0.09 m/s at functional residual capacity (FRC). These values of wave speed fall well within the range of available literature.     

Measurement of optical penetration depth and refractive index of human tissue

Experimental techniques for measurement of optical penetration depth and refractive index of humantissue are presented, respectively. Optical penetration depth can be obtained from the measurement ofthe relative fluence-depth distribution inside the target tissue. The depth of normal and carcinomatoushuman lung tissues irradiated with the wavelengths of 406.7, 632.8 and 674.4 nm in vitro are respectivelydetermined.In addition,a novel simple method based on total internal reflection for measuring therefractive index of biotissue in vivo is developed,and the refractive indices of skin from people of differentage, sex and skin color are measured.Their refractive indices are almost same and the average is 1.533.     

人体不同组织的拉曼光谱研究

测试了人体甲状腺、卵巢、输卵管、肺、子宫平滑肌、子宫颈等组织的拉曼光谱。结果显示,用氩离子激光514.5 nm激发,人体组织拉曼光谱的荧光背景强,在500～3 500 cm-1范围,肺和宫颈组织未显示特征带,甲状腺和子宫组织则显示了较多的带。在600～1800 cm-1范围,子宫、输卵管组织只显示了类胡萝卜素的拉曼带。正常甲状腺组织的光谱和甲状腺滤泡癌组织的光谱之间显示出明显差异,后者没有呈现1 585和1 634 cm-1特征带;正常肺组织与肺癌组织的拉曼光谱也有较大区别,肺癌组织的光谱强度比正常组织的低得多。拉曼光谱技术在临床医学诊断方面将会发挥重要的作用。     

超极化气体肺部磁共振成像

磁共振成像(MRI)技术具有非侵入、无放射性的特点,在临床疾病诊断中具有独特的优势,但是肺部空腔的特殊结构使传统质子MRI无法对其直接成像.自旋交换光抽运(SEOP)方法可以使惰性气体原子的极化度增强4个量级以上,从而使肺部的气体MRI成为可能.该文介绍了超极化惰性气体肺部MRI的最新研究进展,包括超极化气体磁共振相关参数的测量方法、肺部通气结构成像、肺部气体交换功能成像,同时比较了常用于肺部MRI气体的优点和缺点.     

129Xe NMR in study of tissues and plants

The high sensitivity of the¹²⁹Xe nuclear magnetic resonance (NMR) chemical shift to the environment was used for characterization of biological tissues and plants. The xenon gas was dissolved under moderate pressure by means of a special device in small pieces of human and animal tissues (heart, muscle, lung, kidney, liver, spleen, brain, sinew, cartilage and hypodermic fat) or plants (leaves, stems, grains, fruits) and the NMR parameters were measured in vitro. The observed line with the chemical shift ～ 180 ppm was attributed to the xenon located in various cellular structures such as lipid shells, intracellular formations. A xenon spectrum in the lungs obtained in vitro coincides with that in the lungs of a mouse measured in vivo by other investigators. The NMR parameters were found to reveal noticeable distinctions between normal and tumour-affected tissues. The analysis of the¹²⁹Xe NMR spectra of the sinew and the cartilage revealed the dependence of the magnetic parameters on the age of the substance. This fact could be accounted for by the changes of the absorption ability of a biological system due to age transformations. The results obtained in comparison with biochemical data reveal the promissory outlook of¹²⁹Xe NMR for the investigation of the state of biological tissues and for medical diagnostics.