Tunable-optical-filter-based white-light interferometry for sensing

We describe tunable-optical-filter-based white-light interferometry for sensor interrogation. By introducing a tunable optical filter into a white-light interferometry system, one can interrogate an interferometer with either quadrature demodulation or spectral-domain detection at low cost. To demonstrate the feasibility of effectively demodulating various types of interferometric sensor, experiments have been performed using an extrinsic Fabry-Perot tunable filter to interrogate two extrinsic Fabry-Perot interferometric temperature sensors and a diaphragm-based pressure sensor.     

Microwave metamaterial absorber for sensing applications

A metamaterial absorber (MA) based sensor is designed and analysed for various important applications including pressure, temperature, density, and humidity sensing. Material parameters, as well as equivalent circuit model have been extracted and explained. After obtaining a perfect absorption (PA) at around 6.46 GHz and 7.68 GHz, surface current distributions at resonance points have been explained. Since bandwidth and applicability to different sensor applications are important for metamaterial sensor applications, we have realized distinctive sensor demonstrations for pressure, temperature, moisture content and density and the obtained results have been compared with the current literature. The proposed structure uses the changes on the overall system resonance frequency which is caused by the sensor layer’s dielectric constant that varies depending on the electromagnetic behaviour of the sample placed in. This model can be adapted to be used in sensor applications including industrial, medical and agricultural products.     

Optical sensing by silicon slot-based directional couplers

A theoretical investigation of an optical liquid sensor, based on asymmetric directional coupler employing slot optical waveguides, is carried out. The sensing principle is based on the shift in the waveguide transmitted spectrum induced by analyte refractive index change. Silicon-on-insulator technology has been assumed in sensor design, and sensor modelling is carried out by using the coupled modes theory and the finite element method. The influence of geometrical parameters on the sensor characteristics has been investigated. A minimum detectable refractive index change of the order of 10^?6 can be theoretically predicted.     

Precise relative rotation sensing using slow light

A novel relative rotation sensor based on slow light is proposed and analysed. A theoretical analysis shows that the high sensitivity of the proposed rotation sensor is achieved through an electromagnetically-induced-transparency medium. Unlike the tradition detection method, the idea of rotation sensing is to detect group delay between counterpropagating wave packets. It can be used to realize an ultra-precise rotation sensor.     

温度不敏感的光纤布拉格高压传感技术研究

 为了实现单一光纤光栅对压强精确测量,设计了一种温度不敏感的光纤布拉格高压传感器。对该传感器的温度特性及压强响应特性进行研究。给出了该传感器的结构及封装方法。从理论上分析了该传感器的温度去敏原理,推导了该压强传感器的光纤布拉格光栅中心波长与压强的关系,得到了该传感器的压强响应灵敏度的解析表达。通过实验分析传感器的温度特性及压强响应。实验结果表明,在21℃～260.8℃的范围内,实现了温度补偿,平均波长漂移量为0.75 pm/℃,在0～44 MPa的范围内,获得了-0.054 8 nm/MPa的压强响应灵敏度,是裸光纤布拉格光栅压力响应灵敏度的18.27倍。该传感器的压强响应具有很好的线性和重复性,实验值与理论值吻合得很好,该传感器能够通过一只光纤布拉格光栅实现压强的精确测量。     

用于电流传感的声表面波磁致伸缩效应

利用声表面波(SAW)磁致伸缩效应可以实现一种快速、高灵敏度的电流检测方法,但磁致伸缩薄膜内部矫顽力导致了明显的磁滞误差。磁致伸缩薄膜的栅阵化设计可以减小磁致伸缩时薄膜内部矫顽力,抑制磁滞现象,从而实现高灵敏和低迟滞误差的SAW电流检测。结合有限元和耦合模理论对沉积铁钴(FeCo)薄膜栅阵的声表面波电流传感器中的磁致伸缩效应进行分析,对传感响应进行仿真,确定优化的传感结构参数。为验证理论分析,实验研制了频率为150 MHz的声表面波电流传感器件,并结合差分振荡电路及亥姆霍兹线圈,建立传感器测试系统.实验结果表明,磁致伸缩薄膜的栅阵设计大幅降低了迟滞误差,并显著提升了传感器灵敏度。      

Fibre-optic digital single point temperature sensing element

This note describes a fibre-optic digital temperature sensor which employs the change in absorption coefficient observed when a material undergoes a solid/ liquid phase transition. The sensor response is shown to display characteristics which are digital in nature and suitable for many industrial applications.     

Fiber-optic sensing of high static pressure

Abstract

This paper describes a new fiber-optic sensor for pressures up to 200 MPa, based on the effect of hydrostatic stress on the polarization-mode coupling which occurs in highly birefringent fibers. Sensor construction, measurement set-up and typical output are presented. Results show that this new sensor displays far greater sensitivity when compared to solid-state pressure sensors.     

A piezoelectric array for sensing radiation modes

With an example of simply supported beam, this paper presents new experimental wok that is to sense radiation modes by a piezoelectric array. An array of rectangular segments of PVDF film attached on the surface of the beam are taken as sensor. The output signals of the PVDF films are multiplied by appropriate weights so that the weighted combinations of the outputs directly lead to the radiation mode amplitudes of the beam. The weight of every PVDF film sensor is independent of the type, magnitude and position of the external excitation. Experimental results are also presented to show the feasibility of this new type radiation mode sensor.     

Pressure sensing utilizing linear cavity erbium-doped fiber laser

In this paper, we report a fiber laser pressure sensor based on linear cavity erbium-doped fiber laser. The fiber laser structure comprises of an erbium-doped fiber amplifier, a circulator, an optical coupler and a fiber Bragg grating (FBG) which acts simultaneously as a lasing wavelength selecting components as well as a pressure sensor. The FBG is fitted to the shock tube where the pressure is applied. The fiber laser pressure sensor has a low threshold power of 7 mW, an output power of 2.28 mW and an optical signal to noise ratio over 55 dB. The proposed fiber laser sensor is expected to be an attractive choice for long-distance pressure monitoring.     

Electrocatalytic sensing of omeprazole

Ionics - A novel, simple, sensitive, and highly selective omeprazole sensor based on the synergistic effect of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) has been developed. The...     

基于弯曲伸张结构的光纤光栅传感研究

以民用工程结构如桥梁、大坝、高层建筑的健康检测为背景, 采用光纤光栅传感器实现对结构性能的实时监测和诊断, 及时发现结构的损伤以评估结构的安全性. 提出了一种可用于光纤光栅传感的新型弯曲伸张弹性敏感结构, 可实现对压力、应变以及加速度的准确测量. 对该结构弯梁腹部处的应变进行了理论分析和实验验证, 结果表明弯梁腹部处各点的应变与该弯曲伸张结构在竖直方向上所受压力、应变以及加速度大小成线性关系. 其最大的优点是同样灵敏度下体积小, 在井下等横向尺寸受限、又要测量纵向加速度的情况下, 梁式传感结构很可能无法使用, 该新型弯曲伸张型弹性敏感结构可作为弹性元件用于光纤光栅压力、应变、称重以及加速度传感器的设计.     

Linear phase retrieval for wave-front sensing

Phase retrieval from one or more intensity measurements is a potentially powerful and appealing technique for real-time adaptive-optics wave-front sensors. Under the assumption of small wave-front phase excursions, one is able to derive an exact solution to the inverse problem given three or more intensity measurements with known phase offsets. Applications include a high-order wave-front sensor to correct for residual aberrations in an adaptive-optics system in tandem with a low-resolution Hartmann-Shack wave-front sensor. The formula can also furnish mathematical insights into the full nonlinear phase-retrieval task.     

“神舟”四号中的微波遥感

多模态微波遥感器是我国第一次进入太空的微波遥感器 ,是一部集高度计、散射计和辐射计为一体 ,具有综合观测能力的微波遥感器 .经过“神舟”四号飞船的在轨运行实验 ,取得了大量的有效科学数据 ,在轨实验获得成功 .文章介绍了多模态微波遥感器的基本工作原理、系统组成和运行控制模式 ,给出了主要技术和应用指标 ,总结了多模态微波遥感器在轨运行情况 ,给出了初步实验结论     

基于CCD与CMOS的图像传感技术

概述了CCD图像传感器的原理、特点及发展趋势。对CMOS图像传感器的结构和工作原理,尤其是CMOS与CCD两类图像传感之间的不同进行综述。重点介绍了CMOS图像传感器的研究现状和发展趋势。     

石英音叉温度频率特性的温度传感器（英）

提出了一种基于石英晶体温度频率特性的石英音叉微谐振式温度传感器。通过理论分析的方法对传感器进行设计,并采用有限元仿真对传感器的结构参数进行优化。采用光刻和蚀刻微加工技术制造石英音叉谐振器,对石英音叉温度传感器样机的频率温度特性进行实验研究。实验结果表明:石英音叉温度传感器的标准谐振频率为36.545 kHz,灵敏度为-1.9 Hz/℃,在-20到100 ℃的温度范围内,其非线性误差小于0.18%,迟滞为0.02%,与理论研究相吻合。该传感器具有高精度、高灵敏度、低功耗和低成本的特点,为高性能温度测量提供较好的解决方案。     

Chemical sensing with microbent optical fiber

We propose and demonstrate the possibility of using a permanently microbent bare optical fiber for detecting chemical species. Two detection schemes, viz., a bright-field detection scheme (for the core modes), and a dark-field detection scheme (for the cladding modes) have been employed to produce a fiber-optic sensor. The sensor described here is sensitive enough to detect concentrations as low as nanomoles per liter of a chemical species, with a dynamic range of more than 6 orders of magnitude.     

Line-laser-based yarn shadow sensing break sensor

In this paper, a line-laser-based yarn break sensor is proposed. In the proposed sensor, yarns are illuminated by a line laser placed on one side of the yarn plane. A screen is placed on the other side and the image formed on the screen is detected by a camera. The total number of yarns is compared with the total number of shadows formed by the yarns or the total number of light spots formed due to the distances between yarns. If the total number of yarns to be detected is greater than the total number of shadows or light spots formed due to the distances between the yarns, the sensor warns of breaking. In the proposed method, evaluation is made using only light spots or shadows formed by the yarns. Consequently, the yarn type, structure, color, or dimensions do not affect the results.Design principles of the line-laser-based yarn break sensor, which consists of a screen and a Charged Coupled Device (CCD) camera, are presented. The screen displays the shadows formed by the yarns and the light spots formed due to the distances between them. The CCD camera detects the image on the screen. Formation of the shadows by the yarns is explained and an analytical formula that expresses the dimensions of the shadows is obtained. The detection area of the sensor is expressed relative to the total number of yarns, yarn thickness, and distances between the yarns. Line laser radiation angle and light spot intensity equations are obtained relative to the width of the detection area and the height of the line laser placement. The screen length is obtained relative to the number of yarns and the placement of the laser, the yarn plane, and the screen.Different placement situations of the line laser (transmitter), the screen, and the CCD camera (receiver) relative to the yarn plane are discussed. An experimental setup is developed to test the system. The image formed on the screen is studied.     

Axially distributed sensing for three-dimensional imaging with unknown sensor positions

Recently, an axially distributed sensing system was proposed for three-dimensional (3D) imaging where the sensors are distributed along the optical axis. In this previously reported system, a priori knowledge of exact sensor positions was required for 3D image reconstruction. In this Letter, we present an axially distributed sensing with unknown sensor positions along the optical axis. In this system, only the relative positions of two sensors are needed, whereas all other sensor positions are assumed unknown. Experiments are presented to illustrate the feasibility of the proposed system and illustrate the visual quality of reconstructed 3D images by using the proposed calibrated sensor positions. To the best of our knowledge, this is the first report on axially distributed sensing with unknown sensor positions.     

基于CMOS图像传感器的可见光遥感相机原型系统设计

遥感器是遥感技术应用的基础设备,它决定了遥感系统的成像质量。介绍了光电传感器在可见光遥感中的应用,阐述了光电遥感器的结构与关键技术,提出了CMOS数字传感器在遥感领域应用中所具有的优势,设计并实现了基于CMOS传感器的光电成像原型系统。结果表明,遥感相机的图像获取、数据存储的基本功能为CMOS在可见光遥感应用中的相关问题提供了研究平台和技术储备。