光纤倏逝波生物传感器探针新的几何设计

为提高光纤倏逝波生物传感器的探测效率和灵敏度,根据光纤的模式匹配理论计算了给定条件下光纤探头的模式匹配半径,以此匹配半径为基础分析激发光在线性锥型光纤探头中的光线传输轨迹.结合倏逝波透射深度与光线入射角之间的关系,提出一种新的抛物线锥形光纤探头.计算结果表明,为使入射光在均匀感应部分激发的能量最大,入射角在锥形感应部分必须满足在锥形终端最小且刚好是临界角的条件.通过修正抛物线锥形参数,使入射角在满足全反射条件下更加接近于临界角,从而获得比线性锥形更深的透射深度.灵敏度测试实验结果表明抛物线锥形的灵敏度比其它探针测试效果好,说明凹形抛物线锥形探针能够与待测的生物样品之间构成一种理想的荧光收集与激发机制,实验与理论结果比较吻合.     

本征型光纤倏逝波化学传感器的研究

为了克服传统光纤化学传感器的不足,本文提出基于倏逝波原理的本征型光纤化学传感器。根据光线理论数值分析了传感器几何结构参数,溶液折射率与灵敏度的关系。通过化学腐蚀方法制备出不同参数结构的传感器,进行实验系统设计,并用不同浓度亚甲基蓝对这些传感器进行了实验研究。实验结果与数值计算结果一致,传感区纤芯越细,越长,其灵敏度越高。为了提高传感器灵敏度并保证纤芯不至于太细而折断,应少减小传感器直径,有效增加其长度。     

光纤倏逝波吸收传感器灵敏度模拟分析

基于光波导模式理论,结合光纤倏逝波吸收原理,分析了本征型单模光纤倏逝波的传输特性及功率传输情况,导出了光纤倏逝波吸收传感器的灵敏度公式。结合灵敏度公式分析了传感器的几何参数、溶液折射率及入射波长与灵敏度的关系,运用时域有限光束传播法（FD BMP）进行模拟。模拟结果表明,光纤传感区纤芯越长越细,外界溶液折射率越小,入射波长越短,其归一化输出功率越小,传感器灵敏度越高,这与理论计算和文献实验结果一致,为光纤倏逝波吸收传感器的研究提供了参考。     

新型的分段结构光纤倏逝波传感器

提出一种基于倏逝波吸收原理的分段结构光纤倏逝波传感器。运用光束传播法(BPM)对分段和直形波导模型进行数值模拟,分段波导中高阶模在每次分段的第一个界面上被反复地激发。分析不同结构、纤芯直径和溶液浓度对传感器灵敏度的影响,通过化学腐蚀方法制备出不同结构参数的倏逝波传感器,并用不同浓度亚甲基蓝溶液对传感器的灵敏度特性进行实验验证。实验结果表明,在传感直径相同的条件下,传感长度为5cm分段结构光纤倏逝波传感器的灵敏度为0.0135L/mmol,优于传感长度为6cm的传统的单一直形传感器的灵敏度0.0102L/mmol。分段结构光纤倏逝波传感器能有效地激发光纤中低阶模到高阶模的转变,从而提高传感器的灵敏度。实验结果与模拟和理论结果相符。因此,分段结构光纤倏逝波传感器相对于传统的单一的直形传感器不仅具有较高的灵敏度,且机械强度较高,在物质光谱检测方面有着潜在的应用。     

倏逝波光纤布拉格光栅归一化反射率特性研究

基于光波导理论与光纤布拉格光栅（FBG）的模式耦合理论,对倏逝波FBG传感器的能量衰减特性进行了分析研究。最后得到了FBG的归一化反射率的表达式,它是外部介质折射率（SRI）和FBG纤芯直径的函数。理论仿真显示FBG归一化反射率会随着SRI增大和FBG腐蚀程度的加深而减小,呈非线性关系。实验结果也证明增大SRI（小于包层介质折射率）或者增大FBG的腐蚀程度都会使光纤纤芯中的传输能量减小,增强倏逝波与外部媒介的相互作用,从而增加传感器的灵敏度。     

光纤倏逝波化学传感器灵敏度特性研究

为了克服传统光纤化学传感器的不足,运用宽光谱分析法设计一种基于倏逝波原理的光纤化学传感器,研究了传感器的几何结构参数,溶液浓度与灵敏度的关系。运用光束传播法(BPM)分析传感器几何结构参数与灵敏度的关系;通过化学腐蚀方法制备出不同参数结构的传感器,并用不同浓度亚甲基蓝溶液对这些传感器进行实验验证。实验结果表明,模拟结果与实验结果相符,溶液浓度越大,传感区纤芯越细、越长,灵敏度越高;文章提出的光纤倏逝波化学传感器在水质检测方面有着潜在的应用。     

线性锥形光纤倏逝波传感器的灵敏度分析

倏逝波的透射深度、均匀感应区域的感应芯径和感应长度是线性锥形光纤倏逝波传感器灵敏度的主要影响因素。为了实现灵敏度的最优化设计,分别建立了倏逝波透射深度与锥形参数之间关系及有效吸收路径与感应芯径和感应长度之间关系的数学模型,讨论了不同锥形参数(发射角、锥度比、锥长)下倏逝波的透射深度,不同感应芯径和感应长度下倏逝波的有效吸收路径,并进行了仿真。仿真结果表明,选择锥形光纤几何体和合适的发射角,可使透射深度增大近3倍,当锥度比为0.4时,倏逝波透射深度最大;减小感应芯径,增大感应长度可提高倏逝波的有效吸收路径,增强纤芯表面的倏逝波与周围吸收介质的作用强度。研究结果可用来指导制作高灵敏度线性锥形光纤倏逝波传感器。     

光纤光栅倏逝波传感器灵敏度研究

基于光纤布喇格光栅传感原理,分析了倏逝波光纤布喇格光栅(EWFBG)传感器的传感特征,建立了传感器反射波长随环境折射率变化的数学模型,并导出了波长灵敏度函数。结合函数分析了传感器的光纤光栅直径、外界液体折射率与灵敏度的关系,运用模式耦合理论进行模拟。结果表明,光纤传感区域纤芯越细,外界液体折射率与纤芯折射率相差越小,其反射中心波长漂移量越大,传感器灵敏度越高。通过对纤芯直径为6.2μm和8.2μm在1.33¹.46环境折射率范围内的波长响应关系拟合,分别获得了1.25nm和1.14nm的波长变化量,灵敏度数量级为10-51.46环境折射率范围内的波长响应关系拟合,分别获得了1.25nm和1.14nm的波长变化量,灵敏度数量级为10-5¹0-6,论证了分析结论的正确性。为EWFBG折射率传感器的设计、优化及应用提供了参考依据。     

高灵敏度分段结构光纤倏逝波传感器

提出一种基于倏逝波吸收原理的高灵敏度分段结 构光纤倏逝波传感器。运用光束传播法(BPM)对分 段和直形波导模型进行数值模拟,分段波导中高阶模在每次分段的第1个界面上被反复的激 发和吸收。分析 不同结构和溶液浓度对传感器灵敏度的影响,通过化学腐蚀方法制备出不同结构参数的倏逝 波传感器,并用 不同浓度亚甲基蓝溶液对传感器的灵敏度特性进行实验验证。实验结果表明,在传感直径相 同和分段结构传 感器的传感长度3cm短于传统的单一的直形传感器传感长度5cm的条件下,分段结构传感器 的灵敏度是 0.038L/g,优于直形传感器的灵敏度0.026L/g。分段结构光纤倏逝波传感器能有效激发 光纤中低阶模到高 阶模的转变,从而提高传感器的灵敏度。实验结果与模拟和理论结果相符。因此,分段结构 光纤倏逝波传感 器相对于传统的单一的直形传感器不仅具有较高的灵敏度,且机械强度较高。     

纳米光纤传感器

根据纳米光纤的倏逝波传输特性，提出将亚波长直径氧化硅纳米光纤用于光学传感器的研究设想。通过求解Maxwell方程，得到由于周围环境折射率变化而引起的光纤传导模的位相改变，并由此计算传感器的灵敏度。研究结果表明，使用纳米光纤研制传感器，可以获得比微米级光纤或波导传感器更小的结构尺寸和更高的灵敏度。     

陶瓷质电容式压力传感器的研制

本试验采用增韧陶瓷试制成功了一种陶瓷质的电容式压力传感器，由于采用干式设计（无填充液），及厚膜电路ＳＭＴ技术和ＰＦＭ信号传输技术，其外型尺寸、灵敏度、稳定性、抗干扰能力等均大幅度改善，特别是其耐腐蚀、易安装，因此具有极大的推广应用价值。     

Responses of Electric-Field Probes Near a Cylindrical Model of the Human Body

A theoretical and experimental study on the response of an E-field probe near a cylindrical model of the human body has been conducted. The body is simulated with a long cylindrical dielectric shell filled with saline water, and a single E-field probe oriented in various directions, or an orthogonal probe is heated near its surface. The model with the probe is illuminated by a TE or TM plane EM wave. The response of the probe was found to be strongly dependent on the probe location with respect to the direction of the incident EM wave, the probe separation from the model surface, the probe orientation and the polarization of the incident EM wave. The effect due to the dielectric shell on the probe response, with and without the presence of saline water, was carefully investigated. In all cases, the agreement between theory and experiment was found to be very good.     

Design and performance of a noncontacting probe for measurements onhigh-frequency planar circuits

Optimal design of a noncontacting magnetic probe for measurements on the interior of planar high-frequency circuits has been studied, and performance of the probe has been determined. The design was studied using enlarged models tested at frequencies 100 times lower than those of the actual intended use. The nature of its errors has been investigated, and some techniques for error reduction have been found. The accuracy of measurements on circuits with SWR <3.0 is typically 0.8 dB in magnitude and 7° in phase. S-parameter measurements on general two-ports can also be made by using the probe at several different positions on the associated transmission lines. The technique effectively eliminates the problem of de-embedding that arises in other kinds of S-parameter measurements. Examples of measurements with the large model probe are presented and compared with theory. Performance appears to be acceptable for the intended applications     

Variable structure control of a piezoelectric actuator for a scanning tunneling microscope

Scanning probe microscopes are now widely used in the field of material science and engineering for surface imaging at atomic scale. Their principle is based on the surface probing by a sharp tip approached at a nanometric distance of the surface. The probe is fixed to piezoelectric actuators allowing its displacement above the surface. An electronic command of a scanning tunneling microscope (STM) has been designed and tested. The regulation feedback loop of the tunnel current includes an integral controller, as is the case in commercial equipment. An extra control by variable-structure system has been implemented on this electronic command. Its principle is based on the commutation of the feedback sign. The effect on the system performance of the variable structure control is presented and discussed. An STM head has been modeled and all the model parameters have been determined. The model has been validated by comparison of the experimental and simulated responses of the system under excitation.     

A high-sensibility cathode-ray tube for millimicrosecond transients

A high-sensibility cathode-ray tube has been developed for the photographic recording of transients in the millimicrosecond region. The new cathode-ray tube uses a traveling-wave deflection system with magnetic focusing and attains a spot diameter of 0.001 inch. The first models have a sensibility of 0.026 volt/trace width and a writing speed of 10¹¹trace widths/second. Improved production models are expected to have sensibilities of less than 0.02 volt/trace width. In this particular application, sensibility in volts per trace width and writing speed in trace widths per second are the significant performance characteristics. Analysis of the dependency of these on several important parameters in the general cathode-ray tube design shows that the use of a much smaller spot and display than is conventional results in large gains in sensibility. Analysis also indicates that maximum sensibility is achieved with the deflection plates located in the lens region. Magnetic focusing is used to permit this optimum deflection plate location. To allow the choice of long plates with short effective transit time, a traveling-wave deflection system is employed. Postdeflection acceleration is introduced to obtain high writing speeds.     

Probe correction of spherical near-field measurements

Probe correction has been implemented in a computer program which calculates antenna far fields from spherical nearfield measurements. The computer program has been applied to near-field measurements on a satellite model, and the accuracy of the computed far field is significantly improved, compared with the results obtained without probe correction.     

一款基于凌阳61单片机的汽车弯道会车雷达设计

介绍了一款3cm微波汽车弯道会车雷达的设计方案。该雷达以凌阳61单片机为核心,充分利用凌阳61单片机的DSP处理功能和语音处理功能。该装置安装在行驶的汽车上,使行驶的汽车在弯道处能自动探测出前方行驶车辆,有效避免汽车出现会车险情。该装置结构简单,灵敏度高,适用于行驶在山区公路的各种汽车。     

板级电路模块振动结构优化技术研究

以特定板级电路模块为研究对象,建立有限元模型.运用ANSYS分析软件对影响板级电路固有频率的主要结构参数进行灵敏度分析,从而得到各设计参数和板级电路模块一阶固有频率的关系.然后以灵敏度分析为理论依据进行结构优化设计,在优化过程中,目标参数逐步逼近于最优解,每一步优化设计变量求取新的灵敏度来确定搜索方法,然后进一步优化,从而使设计参数能很快达到最优解或较优化解.     

Nondestructive high-resolution microwave imaging of biomaterials and biological tissues

A high-Q near-field probe based on the 2D microstrip line geometry using defected ground structure (DGS) has been proposed and experimentally evaluated for nondestructive characterization and high-resolution imaging of biomaterials and biological tissues. The unique specifications of the probe are as follows; small size, simple fabrication, non-contact with a sample, excellent de-coupling from surroundings and high microwave power is directly coupled into the tissues. Experimental results show that the probe is able to detect the microwave characteristics of thin lossy biomaterials containing water. High resolution microwave images of leaves with different water content have been obtained with amplitude contrast of about 40–50 dB and spatial resolution of about λ/40. Also, a measurement scenario for detection of lipomas with different sizes has been investigated. Results show that the proposed probe can detect the lipoma of a size larger than 5 mm. Finally, an artificial model to detect skin cancer at the early stage is developed using layers of raw chicken skin. Measurement results show that the probe could accurately detect malignant tumor with at least 15 dB magnitude and more than 100° phase contrast from the healthy skin and with about 8 dB contrast from the benign lesions of the same size.     

激光数字化仪的光学系统设计

本文根据光点扫描测量技术,提出一种新型的激光数字化光学探头,它是利用小型半导体激光器和高分辨率光电探测器件CCD设计而成的。它可对自由模具表面进行快速的、非接触的、精密的测量,提取三维NC(numerical control)数据。其光学系统设计使用了针对特殊光路编写的光学CAD软件。