漫射光强度涨落测量皮肤烧伤深度的模拟实验研究

实验研究了背散射光强度相对涨落与模拟皮肤烧伤深度的关系,结果表明随着模拟烧伤层厚度的增加,背散射光强度的相对涨落逐渐减小。该方法为非接触测量皮肤烧伤深度提供了一种新的参考。     

波长粗糙度与光散射

分析计算了只改变一个参数而其他条件不改变情况下,光学表面光散射的特性.发现:当入射光波长增加时,散射光强相对比率减弱;当表面粗糙度增加时,散射光强相对比率增强.     

波长粗糙度与光散射

分析计算了只改变一个参数而其他条件不改变情况下，光学表面光散射的特性．发现：当入射光波长增加时，散射光强相对比率减弱；当表面粗糙度增加时，散射光强相对比率增强．     

球形粒子的散射和偏振特性研究

利用黎卡地贝塞尔函数模拟了不同粒子尺度的散射光强和偏振特性.当粒子尺度增加时,散射光强增加;水平偏振变得不对称,而垂直偏振没有变化;当粒子的折射率虚部增加时,散射光强减少.从粒子的这些散射特性和偏振特性,可以测量和分辨不同尺度的粒子.     

用微区光学方法研究GaP:ZnO红光外延片

用微区光致发光和拉曼散射光谱比较了国内外Gap:ZnO红光二极管产品的结构，在国内首先实现了用微区光学方法检测LED外延片并进行生产工艺的改进，对典型样品进行了微区光致发光的测试，比较外延片横截面上不同厚度层的光致发光，非常明显地看出主要发光区是在P区。通过合理扩展P层发光区的厚度相应地增加了光致发光的总光强，提高了产品的生产成品率。     

光盘信息坑散射光强的测量

波导多层存储是一种三维光存储技术，如何对光盘信息坑散射光强的测量是其须解决的关键技术之一。本文介绍了利用光学共轭技术测量光盘单个信息坑散射光强的实验原理，给出了采用光电倍增管测量光盘信息坑散射光强的实验结果。结果表明，利用该装置可以检测光盘有无信息坑时散射光强的变化，实现对信息坑散射光强及信息坑的测量，测出信息坑的大小与理论值一致。     

薄膜SOI MOS器件阈值电压的解析模型分析

研究了薄膜全耗尽增强型 SOIMOS器件阈值电压的解析模型 ,并采用计算机模拟 ,得出了硅膜掺杂浓度和厚度、正栅和背栅二氧化硅层厚度及温度对阈值电压影响的三维分布曲线 ,所得到的模拟结果和理论研究结果相吻合。     

硅衬底厚度和背接触势垒高度对MOS电容器性能的影响

通过解一维泊松方程,对均匀掺杂的P型硅衬底MOS电容器进行了数值模拟,研究了衬底厚度和背接触势垒对衬底内的电势分布和载流子密度分布的影响.模拟计算结果表明,在硅衬底厚度超过两倍最大耗尽层厚度时,背接触与正界面之间存在一个电中性区,背接触不会影响MOS电容器的性能;在硅衬底的实际厚度比两倍最大耗尽层厚度要小的情况下,背接触势垒对MOS电容器性能有明显的影响:当背接触势垒高度为零伏或负值时,MOS电容器的强反型阈电压随着硅衬底厚度的减薄而增加;当背接触势垒高度为正值时,随着硅衬底厚度的减薄,会出现阈电压先减小后增加的现象.     

不同工作温度下a-Si(n)/c-Si(p)/uc-Si(p )异质结太阳能电池微晶硅背场的模拟计算与优化

采用Afors-het太阳能电池异质结模拟软件,模拟了在不同工作温度下微晶硅背场对a-Si(n)/c-Si(p)异质结太阳能电池性能的影响。结果表明,随着背场带隙的增加,开路电压和转化效率都增大。随着背场掺杂浓度的增加,开路电压、填充因子和转化效率都在不断地增加;随着背场厚度的增加,电池性能有所下降。随着电池工作温度的上升,微晶硅背场所对应的最佳浓度掺杂值和最佳厚度值变化不大。但是随着温度的上升,微晶硅背场所对应的最佳带隙值有明显的右移趋势。实验结果为电池的商业化生产提供了实验参数。     

激光探测尾流微气泡的偏振特性研究

为了研究尾流中激光照明气泡幕的散射光强度和偏振的特性,利用基于偏振光传输的蒙特卡洛模型,对偏振激光入射含气泡群水体的三维空间分布模式进行仿真计算。研究了气泡和气泡群在不同气泡尺度,不同散射角条件下的散射光强和偏振状态;分析了气泡幕的气泡数密度,厚度对于散射光强度和偏振状态的影响。研究表明,散射光的强度和偏振度对气泡尺度和散射角较为敏感,气泡尺度参数越大,散射光强和偏振特征越趋向于集中在传输方向的小角度散射;气泡幕的数密度和厚度越大,散射光的强度随散射角度变化的敏感度下降,退偏振效果增强。     

Monte Carlo modeling for implantable fluorescent analyte sensors

A Monte Carlo simulation of photon propagation through human skin and interaction with a subcutaneous fluorescent sensing layer is presented. The algorithm will facilitate design of an optical probe for an implantable fluorescent sensor, which holds potential for monitoring many parameters of biomedical interest. Results are analyzed with respect to output light intensity as a function of radial distance from source, angle of exit for escaping photons, and sensor fluorescence (SF) relative to tissue autofluorescence (AF). A sensitivity study was performed to elucidate the effects on the output due to changes in optical properties, thickness of tissue layers, thickness of the sensor layer, and both tissue and sensor quantum yields. The optical properties as well as the thickness of the stratum corneum, epidermis, (tissue layers through which photons must pass to reach the sensor) and the papillary dermis (tissue distal to sensor) are highly influential. The spatial emission profile of the SF is broad compared that of the tissue fluorescence and the ratio of sensor to tissue fluorescence increases with distance from the source. The angular distribution of escaping photons is more concentrated around the normal for SF than for tissue AF. The information gained from these simulations will be helpful in designing appropriate optics for collection of the signal of interest.     

湍流脉动对圆射流红外辐射特性的影响研究

为研究湍流脉动对高温燃气圆射流红外辐射强度的影响,利用大涡模拟方法计算了高温圆射流流场的温度和组分浓度等的瞬时值和平均值,在此基础上分别采用平均温度?辐射法和瞬时温度?辐射法计算了射流场的红外辐射特性。计算结果表明:瞬时温度?辐射法计算的平均光谱辐射强度、平均积分辐射强度和平均辐射亮度均高于平均温度?辐射法计算的结果;湍流脉动越大,掺混区越厚,两种方法的计算结果之间的差值以及射流场红外辐射的脉动幅值均越大,其中射流高温核心区尾缘附近是受湍流影响最强的区域;两种方法计算的平均红外辐射亮度之间的差值沿着径向逐渐降低。对于Re=86 000,环境温度与进口温度之比为0.35的圆射流,在90°探测方向上,瞬时温度?辐射法计算的总的平均积分辐射强度比平均温度?辐射法的计算结果高23.6%左右。     

Teflon/SiO2 bilayer passivation for improving the electrical reliability of pentacene-based organic thin-film transistors

We demonstrate a bilayer passivation method using a Teflon and SiO₂ combination layer to improve the electrical reliability of pentacene-based organic thin-film transistors (OTFTs). The Teflon was deposited as a buffer layer using a thermal evaporator that exhibited good compatibility with the underlying pentacene channel layer, and can effectively protect the OTFTs from plasma damage during the SiO₂ deposition process, resulting in a negligible initial performance drop in OTFTs. Furthermore, because of the excellent moisture barrier ability of SiO₂, the OTFTs exhibited good time-dependent electrical performance, even after 168 h of aging in ambient air with 60–80% relative humidity.     

皮肤表皮厚度对微循环测量的影响

由皮肤散射形成的动态激光散斑携带了微循环的信息。散斑的时间涨落不仅与血球运动。照明条件等因素有关,也与表皮的厚度有关,所以表皮厚度的不同将影响微循环的测定。本文从实验上研究了皮肤表皮厚度对微循环测量的影响,得了了散斑强度涨落随表皮厚度变化的关系。     

基于色相算法的表面等离子体共振成像传感器

本文报道了一种基于色相算法的彩色表面等离子体共振(SPR)成像传感器,该传感器不仅能够对发生于SPR芯片表面的物理化学反应进行直观的图像观测,还能基于色相算法对这些表面反应进行定量分析。利用自制的波长/图像同步检测型SPR传感器,实验获得了不同共振波长对应的共振图像,然后借助色相算法求得每一幅共振图像对应的二维色相分布及其平均色相,建立了共振波长与图像平均色相的依赖关系,用于优化基于色相参数的SPR折射率灵敏度。实验选择起始共振波长为650nm,测得基于色相的折射率灵敏度为3 338/RIU,是基于共振波长的折射率灵敏度的1.49倍。利用彩色SPR成像技术能够直观地观测到金膜表面涂布的聚四氟乙烯薄膜的不均匀性,再通过计算图像局部区间的平均色相,可以定量获得不同薄膜厚度对应的折射率灵敏度。实验结果证明了基于色相算法的彩色SPR成像传感器明显优于常规SPR传感器。     

Reducing temporal fluctuation of signal intensity in optical wavemixing

In electrical amplifiers, the common method to reduce the fluctuation of the output signal is known as feedback. We show that, in optical wave-mixing systems where the total energy of the pump and the signal is conserved, the fluctuation of the signal intensity can be greatly reduced by returning a portion of the output pump to the input pump. The advantage of the latter method is that the signal intensity is not reduced, whereas in the former method the output of the signal is reduced by the same factor as its relative fluctuation is reduced     

Low-Frequency Noise Characteristics in Strained-Si nMOSFETs

The low-frequency (LF) (1/f) noise mechanism of strained-Si nMOSFETs grown on relaxed Si_1-xGe_x virtual substrates (VSs) has been investigated. It is found that the Si-cap thickness plays an important role in characterizing the 1/f noise mechanism. Ge out-diffusion effect and slight strain relaxation in Si-cap layer are responsible for the degradation of 1/f noise in strained-Si device with 10- and 20-nm-thick Si-cap, respectively. In addition, by choosing proper Si-cap thickness, experimental result shows that as Si-cap undergoes stronger tensile strain for higher Ge concentration VS, the correlated mobility fluctuation term in the modified carrier-number fluctuation model is more dominated for the 1/f noise     

A Numerical Evaluation of the Limitations of the Thin-Sheet Approximation

One of the prime difficulties encountered in magnetotellurics involves adequately modeling the conducting earth when lateral conductivity variations are present. A common modeling technique that is used when the horizontal conductivity variations are of limited vertical extent is known as the thin-sheet approximation. The validity of the thin-sheet approximation is examined by comparing the surface impedance obtained for a horizontally layered earth model and its thin-sheet equivalent. Only a homogeneous thin sheet is considered; thus, the effects on the thin-sheet approximation of horizontal conductivity variations within the thin sheet are not evaluated. For the homogeneous thin sheet, it is found that generally the thinsheet approximation yields less than 10-percent error in the surface impedance for frequencies such that the thickness of the layer being modeled by the thin sheet is less than 0.3 of a skin depth in the layer, although in some instances the error approaches ten percent at larger ratios of layer thickness to layer skin depth. The presence of a shallow, highly conductive substratum does not adversely affect the validity of the approximation in many cases, contrary to what was previously believed. In those instances where the conductive substratum does have an effect, it is to reduce the ratio of layer thickness to layer skin depth at which the approximation is valid, and not to invalidate the procedure altogether.     

Amplifying of surface plasmon-polariton in a metal–gain medium–vacuum structure

Propagation of a surface plasmon-polariton in a three-layer system consisting of the half-space filled with a metal, a layer of the gain medium of a finite thickness, and a half-space filled with vacuum is considered. The existence of the optimum thickness of the amplifying layer at which the plasmon is amplified several times stronger than in the case of infinite thickness is demonstrated. In particular, the plasmon loss can be compensated at a lower pumping intensity than in the case of infinite thickness of the gain layer.