Fiber-optic magnetic sensor utilizing the Lorentzian force

A fiber-optic magnetic sensor whose design is based on the Lorentzian force is presented. Optical phase sensitivities of 0.67 and 0.11 rad/(A/m) for AC and DC magnetic fields are obtained with a linearity of three decades using 100 mm of Al-coated sensor fiber. A configuration for multipoint AC field measurement with frequency-independent sensitivity is proposed. Electric current is measurable with a 2.6-rad/μA sensitivity     

A fiber-optic magnetic gradiometer

A fiber-optic magnetic gradiometer capable of measuring both ac and dc magnetic-field gradients has been designed and demonstrated. An approach using real-time magnetic balancing and trimming has been deployed. A device sensitivity of 0.1 gamma (10^-6Oe) per centimeter of sensor head separation for 1 m of magnetically active fiber is achievable.     

Fiber-optic polarimetric DC magnetometer utilizing a composite metallic glass resonator

A fiber-optic polarimetric dc magnetometer has been constructed from 50 m of high birefringence optical fiber. Magnetic fields are detected by the magnetostrictive response of a composite thin-shell resonator consisting of an acrylic tube, unannealed metallic glass ribbon, and a 20-m coil of high birefringence fiber. Quadrature is maintained with the phase tracking technique and optical common-mode rejection is utilized for noise reduction. The rms magnetometer noise corresponds to a minimum detectable magnetic field of 2.6 γ in the dc to 1-Hz bandwidth.     

Precision positioning device utilizing impact force of combinedpiezo-pneumatic actuator

This paper reports on a new actuator combining both a piezoelectric actuator and pneumatic cylinder for the automatic assembly application. The results of fundamental experiments are presented and an analytical model is described. The experimental results show that the proposed actuator can move a target object with step sizes in the 10-nm order by utilizing the impact force of a piezoelectric element while maintaining the comparatively long operation range of a pneumatic cylinder. Furthermore, a 3-DOF positioning system had been constructed as a practical application. Due to the limited sensing range of the gap sensors, the positioning range is limited to ±1 mm, ±1 mm, and ±2 mrad along the 3-DOF. A heuristic control model is described. Using this model, a target object made of stainless steel (130×100×10 mm) was successfully positioned with an accuracy of ±0.5 μm, ±0.5 μm, and ±20 μrad along the 3-DOF. It is shown that the combined piezo-pneumatic actuator has attractive practical applications in the field of precision industry     

Calibration of a multi-mobile coil magnetic manipulation system utilizing a control-oriented magnetic model

In this paper, we address the calibration of a family of magnetic manipulation systems composed of several coils that are moved around by serial robot manipulators. We show in this paper that the calibration of the whole system ultimately results in calibrating the manipulator and coil separately up to an unknown rigid transformation. For calibration of the coil, we propose to use a model that has not been used so far in the literature; a control-oriented model which is sufficiently accurate and computes the magnetic field in real time. A protocol for calibrating the magnetic manipulation system using the Nelder–Mead algorithm to estimate the model parameters is presented. Calibration was performed through simulations and validated experimentally on a physical system. It was observed that the root mean square error was reduced by 37% after calibration of the physical system, indicating an improvement in accurately estimating the magnetic model.     

Side force in coil-sheet magnetic levitation systems

A Fourier transform technique is used to evaluate the forces on planar polygonal dc current coils moving parallel with a conducting sheet as applied to the magnetic levitation of high-speed ground vehicles. In addition to the lift and drag forces usually discussed, a side force may exist if the current coils are asymmetric with respect to the direction of vehicle motion. For some geometrically symmetric coils, the side force may be viewed as a transverse drag which exponentially damps small lateral motion. For some other coils, instability may occur due to a perturbation in the lateral direction. With proper design, a significantly large side force (comparable to drag) may be generated and controlled by mechanical or electrical means. This side force can be used for lateral control purposes.     

Focusing of biological cells utilizing negative dielectrophoretic force generated by insulating structures

The main purpose of the present study is to design an insulator-based dielectrophoretic microdevice with effective focusing of biological cells. The cells are introduced into the microchannel and pre-confined hydrodynamically by the funnel-shaped insulating structures close to the inlet. The cells are, therefore, repelled toward the center of the microchannel by the negative dielectrophoretic forces generated by the insulating structures. The increase in the applied electric field significantly enhances the performance of focusing. Furthermore, decreasing inlet velocity increases the efficiency of focusing because the higher velocity results in more lateral expansion. Preliminary experiments employing viable HeLa cells are conducted in order to demonstrate the feasibility of the present design. Experimental results indicate that the performance of focusing increases with the strength of the electric field applied or with a decrease in the inlet velocity. The experimental results agree with the predictions by numerical simulations. The design proposed herein has no need for complicated flow controls to focus the cells.     

接近表面磁力显微镜成像方法的研究

在当今信息社会时代,需要存储的信息总量正在急剧增加。与光存储技术和半导体存储技术相比而言,磁记录技术占领着几乎90％的存储市场。磁力显微镜( magnetic force microscope,MFM)的发展与磁记录工业密切相关。然而,从1987年至今,MFM的分辨率仍然停留在50~10 nm的水平,传统思路已经很难再实现突破。本论文基于MFM探针的窄带－频率调制机理,发展接近表面磁力显微镜方法,实现对纳米结构中磁畴状态的超高分辨率成像。该工作的关键在于合理利用MFM探针的窄带－频率调制机理,优化设计动态信号处理模块,精确控制探针－样品间距(5 nm 以下),独立分离磁力像和表面像(磁力像为交流信号,原子力像为直流信号),由此测量和解释纳米尺度磁畴结构。该方面的工作对于纳米磁畴结构的设计、核心磁性器件的研究起到非常关键的作用,为下一代磁记录技术的发展提供了新型的有力工具。     

光纤微波传输线

论述如何对折射率导引结构 InGaAsP 激光二极管组件和 InGaAs APD 光电二极管组件设计微波封装。其激光二极管组件特点为同轴 SMA 连结器和50Ω匹配的输入阻抗,还包含一个光功率监视的光探测器,一个热敏电阻,一个温度电致冷器(TEC)等组成“蝶形”单列插针式光缆(纤)耦合全密封封装;光电二极管组件也同样有同轴 SMA 连接器组成共平面波导封装耦合光缆(纤)。两种组件之间使用 FC/PC 标准光缆活动连接器,组成光纤微波传输线实验样机。主要指标:调制频率范围 f 为1.8～5.0GHz,带宽 B>3GHz,峰值波长λ_p 为1300nm,CW 尾纤功率P>1mW,输出阻抗 Z 为50Ω,输出射频功率 P_(RF)>—30dBm,检测灵敏度 S<—70dBm,传输距离 d 为6.5km。     

Fiber-optic strain gauge

Prototype fiber-optic strain gauges consisting of plastic fibers containing permanent microbends were fabricated and various properties were measured. Their strain sensitivity as a function of microbend amplitude is shown, and their transduction mechanism, which is primarily the drop in microbend amplitude under tension and the corresponding increase in the fibers' optical transmission, is discussed     

光纤测试产品

用于测试激光模块的双通道仪表 为测试激光二极管模块而设计的2500系列双通道光敏二极管仪表是实现快速的小电流和光功率测量的仪表。一个内藏的微微表可以测量低至10fA的电流。±10V/±100V电压源给各种光电检测器提供功率。所有的通道都可单独使用,或组合使用来做诸如激光二极管和光纤挠性接头之间的耦合效率的测量。     

微观磁区中磁力线的电子全息观察

用Mollenstedt电子双棱镜作为分束器,磁性镍钢片为测试样品,在JEM-200CX型电子显微镜上记录了微观磁场的电子全息照,由M-Z干涉仪再现,获得了微观磁区的磁力线图。     

Peculiarities of three-passage measurements in magnetic force microscopy

The method of three-passage measurements in magnetic force microscopy is described, which yields refined magnetic images of nano and microobjects, and eliminates the possible parasitic influence of long-range electrostatic forces while obtaining a magnetic image.     

Mean-square error due to gradiometer field measuring devices

Gradiometers use spatial common mode magnetic field rejection to reduce interference from distant sources. They also introduce distortion that can be severe, rendering experimental data difficult to interpret. Attempts to recover the measured magnetic field from the gradiometer output will be plagued by the nonexistence of a spatial function for deconvolution (except for first-order gradiometers), and by the high-pass nature of the spatial transform that emphasizes high spatial frequency noise. Goals of a design for a facility for measuring biomagnetic fields should be an effective shielded room and a field detector employing a first-order gradiometer.     

光纤电压测量仪

利用BGO的横向电光效应研制的光纤电压测量仪,具有高输入阻抗、安全可靠、远距离测量、高精度、高线性度以及可数字和模拟输出等特点。其电压测量范围0—20kV,精度±1%(满刻度),线性度±1％。 本文将叙述其光纤电压测量仪的基本原理、设计考虑、仪器结构及其性能参数。     

Fiber-optic ellipsoidal flextensional hydrophones

Calculations of circumferential strain, polar and equatorial displacement, lowest natural frequency, buckling pressure, and optical pressure sensitivity for an oblate-spheroidal-shell fiber optic hydrophone are presented using the theory for thin shells. Sample designs based on these calculations are compared to other fiber-optic hydrophone designs of similar dimensions and materials. A prolate-spheroidal-shell hydrophone design is also presented     

纤维光路器件

纤维光路器件是整个光纤产业的重要组成部分,它包括光纤通信用无源器件和种类繁多的光纤传感器。本文在阐述多种器件用途的同时,以大量照片与性能参数表明了我国部分光纤器件产品的水平,并指出这一领域研究和开发工作的重要性。     

光纤复合压力计

本文给出了一种光纤复合压力计。该压力计在原有的C型弹簧管机械压力表的基础上,复合了一个光纤传感装置。这种压力计扩展了原机械压力表的功能,特别适合于易燃易爆的石油、化工等场合的压力遥测。测试结果表明,该光纤复合压力计不仅具有良好的重复性,还能自动消除光源强度变化对测量结果的影响。     

Fiber-optic nonlinear coherent coupler

A new type of fiber-optic nonlinear coherent coupler consisting of a low-birefringence fiber and a fiber-optic polarization beam splitter is proposed. The principle of operation is based on nonlinear polarization change in the low-birefringence fiber. The characteristics of the fiber coupler are analyzed using the Stokes parameters formalism on the Poincaré sphere. The coupler is shown to be capable of acting as an intensity discriminator, pulse reshaper, and all-optical gate.     

一种新型光开关交换器

探讨了光偏振现象和旋光现象的特点 ,进而利用偏振和旋光现象提出一种新型光开关交换器。这种交换器具有结构简单、与输入光的偏振态无关、不会产生相位差、插入损耗和信道串扰小、响应速度快、器件体积小等优点 ,同时可以使用此器件和光波分复用 /解复用器相结合 ,方便地实现任意波长的上下路。对 2× 2开关交换器的性能进行了分析 ,结果表明它的插入损耗和信道串话都很小。