A Fiber-Optic pH Sensor for Microbioreactors

Technical Physics Letters - A fiber-optic sensor for microbioreactors has been developed and manufactured that records pH changes in the range from 6.5 to 9 with an accuracy of ±0.2 for small...     

Multiplexed Fiber-Optic Pressure and Temperature Sensor System for Down-Hole Measurement

A fiber Fabry–Perot (F-P) interferometer and a fiber Bragg grating (FBG) based pressure and temperature multiplexing sensor system is presented. This system is designed for high-temperature oil well down-hole permanent monitoring of pressure and temperature. Connecting a FBG temperature sensor and a F-P pressure sensor in series in the sensor head, the sensor system combines the advantages of simple structure of FBG for temperature sensing and high accuracy and low-temperature cross-sensitivity of F-P pressure sensor. Experimental results showed that the temperature measurement accuracy of 0.5$;^{circ}$C and the long-term drift of the air gap of the F-P pressure sensor at 300$;^{circ}$C is less than 0.1% within 300 h time span. This indicates that a long-term pressure measured accuracy of 0.03 MPa has been achieved in pressure gauge range of 0–30 MPa and in temperature variation range between 18 $;^{circ}$C to 300 $;^{circ}$C.      

Fiber-Optic Polarization Pressure Sensor

The highly sensitive polarization pressure sensor is based on single-mode fiber-optic waveguides. The measured sensitivity has been found experimentally to be 13·10_–2 dB·Pa_–1·m_–1. A /4 phase plate was used as an optical decoupler in the sensor.     

智能化光纤压力传感器

介绍了一种根据光纤弯曲损耗原理，以中空螺旋形光纤环作为压力传感元件，用８０９８单片机进行控制和数据处理的智能化光纤压力传感器。其测压范围可通过选用不同刚度的弹性元件加以扩大或缩小，测压准确度为０．５％，重复性、非线性误差均小于０．５％。     

Fiber-Optic Sensor for Web Velocity Measurement

The design and development of a new fiber-optic sensor for measuring the velocity of a continuous material (also called a web) in material processing systems is described. The development of the proposed sensor is based on the dual beam laser Doppler velocimetry technique and the unique properties of different types of optical fibers. The developed sensor is capable of measuring the true web transport velocity as opposed to the existing methods which infer web transport velocity based on the roller angular speed. Since the sensor design utilizes fibers, signal processing can be performed away from the measurement area, and as a result the sensor can be used in harsh environments within the web processing line. The proposed sensor has been constructed and experiments have been conducted on an experimental web platform. The performance of the sensor is evaluated for a range of web velocities and different web materials. Sensor design, its construction, and a representative sample of the results are presented and discussed.     

A Novel Fiber-Optic Tapered Long-Period Grating Sensor for Pressure Monitoring

The method and the required installations for fabricating tapered long-period fiber gratings can be simpler than that of standard fiber Bragg gratings, and the fabrication process is faster. To our knowledge, the tapered long-period fiber grating pressure sensor is presented here for the first time. In this paper, the fabrication method for tapered long-period fiber gratings, the sensing principle, the sensor structure, the measurement setup, and the preliminary results are presented and discussed. The pressure sensitivity of the sensor is as high as 5.1 pm/bar.     

悬臂梁式光纤声传感器研究

光纤声传感器种类很多，但大多着眼于水声，作水听器用。现在本文提出一种可用于空气声检测的悬臂梁式光纤声传感器。本文给出了该种传感器的实验装置，谐振频率，灵敏度的计算，同时给出了它们的实验值。用这种传感器在实验室内可测到最低声正为１×１０－４Ｐａ（１００Ｈｚ时）     

一种新型光纤电流传感器的设计

本文提出了一种新型的高压电流光纤传感器 ,该系统由具有相位压缩原理的Sagnac干涉仪光路构成 ,与通常的干涉仪相比该系统的动态测量范围扩大数百倍 ,而且系统不受外界缓变量的影响 ,系统采用相位切换技术使干涉仪保持在正交干涉状态     

Distributed Fiber-Optic Sensor for Dynamic Strain Measurement

A novel Brillouin-based distributed sensing technique is presented that can obtain the strain profile of the entire sensing fiber with a single optical pulse. Experimentally obtained spectra show that this comb excited pump signal is capable of strain and temperature measurement in a dynamic system. The results show the expected sinusoidal strain profile for a 12 s periodic strain cycle applied to the test fiber. The strain distribution for the entire fiber was obtained in 256 mus , thereby demonstrating for the first time, the potential to measure dynamic strains up to 3.9 kHz with 12 m resolution. Increased acquisition speed comes at the expense of achievable spatial resolution.     

Fiber-Optic Magnetostriction Sensor for Free Oxygen Concentration

A simple design is suggested for a free oxygen sensor capable of recording free oxygen concentration at the level of about 10²² m^–3 with a predicted linear measurement range of four to five orders of magnitude.     

An Active Core Fiber-Optic Temperature Sensor Using an Eu(III)-Doped Sol-Gel Silica Fiber as a Temperature Indicator

An active core fiber-optic temperature sensor has been developed by using an Eu(III)-doped sol-gel silica fiber as a temperature indicator and has been tested for sensing temperature in the range from 80 degC to 500 degC. The fluorescence of Eu(III) doped inside the sol-gel silica fiber was excited with a simple LED with peak wavelength at 420 nm and the fluorescence intensity was recorded as a sensing signal. The fluorescence intensity decreases with the increase of temperature. In the temperature range from 140 degC to 300 degC, the attenuation of the fluorescence intensity of the fiber-optic sensor in decibel has a linear relationship with temperature     

Hydrostatic Fiber-Optic Liquid Level Sensor with a Position-Sensitive Detector

Measurement Techniques - Monitoring of the level of different flammable liquids is examined, including that of petroleum products in high capacity tanks, as well as during pumping, at oil storage...     

A Compact Fiber-Optic Flow Velocity Sensor Based on a Twin-Core Fiber Michelson Interferometer

A novel fiber-optic flow velocity sensor based on a twin-core fiber Michelson interferometer has been proposed and demonstrated. The sensor only is a segment of twin-core fiber acting as cylinder cantilever beam. The force exerted on the cylinder by the slow flow speeds of order mm/s of the fluid with unknown velocity bends the fiber, which corresponds to the shift of the phase of the twin-core in-fiber integrated Michelson interferometer.     

Use of Fiber-Optic Sensor to Record Pulsed Plasma Discharge Current

Measurement Techniques - The need to increase the precision with which the form of the pulse of the rapidly varying current of powerful plasma radiation is recorded under the conditions of powerful...     

基于FBG温度解耦的光纤法布里-珀罗 高温压力传感器

本文提出了一种基于光纤布拉格光栅(FBG)温度解耦方法的光纤法珀(FP)压力传感器,该传感器采用低温共烧陶瓷(LTCC)技术实现批量化制作.通过在膜片式压力传感器的基础上集成光纤布拉格光栅(FBG),实现温度、压力双参数测量;提出温度解耦方法,对传感器进行温度补偿及压力测量结果的修正.实验结果表明,在20～300℃的温度范围内, FBG温度传感器的灵敏度为0.012 nm/℃,在160 kPa的压力范围内,压力测量灵敏度约为0.1μm/kPa, 3次重复实验的重复性误差和非线性误差分别约为5.6%和1.3%,温度系数为0.018μm/℃,压力灵敏度随温度变化为0.283 nm/(kPa·℃),同时,采用温度解耦方法,得到压力计算值与真实值最大偏差小于2.5 kPa.     

光纤直流大电流传感器非线性机理及校准技术

非线性误差是干涉型数字闭环光纤电流传感器超大电流测量的主要误差源之一.借助琼斯矩阵方法,推导了光纤1/4波片不理想条件下传感器输出与被测电流的理论关系,确定了1/4波片的方位角和相位延迟误差是造成光纤电流传感器超大电流测量非线性的主要原因之一.仿真结果表明:在5 ～ 300 kA范围内,方位角误差小于4.53°,相位延...     

Fiber-Optic Sensor Interrogation Based on a Widely Tunable Monolithic Laser Diode

Fiber-optic sensors have experienced great interest in research and development since their invention. Dedicated measurement systems are essential for utilization and development of these sensors. Instruments based on tunable lasers are established devices for the demodulation of such sensors. We introduce and demonstrate a tunable laser measurement system based on a widely tunable monolithic laser diode (TML). It is capable of demodulating different types of fiber-optic sensors, although we focus on the interrogation of fiber Bragg grating (FBG) sensors. The rapid tuning of the laser's wavelength is critical for achieving high measurement rates. However, the high tuning rate is demanding and requires careful characterization. We present a method for this and show, to our knowledge for the first time, data on the rapid tuning through the whole spectrum of this type of laser diode. We propose a modified centroid algorithm that can cope with nonequidistantly sampled spectra caused by the laser's functional principle. Finally, we demonstrate the dynamic performance of the new measurement system in an application: An FBG-based acceleration sensor is demodulated at a 5-kHz sample rate during a vibrational test showing the potential of the approach.      

Highly Sensitive Fiber-Optic Faraday-Effect Magnetic Field Sensor Based on Yttrium Iron Garnet

1. IntroductionFaraday-effect sensors have been developed during the past 15 years to measure electric current andmagnetic fi.ldllL31. In these sensors) much attentionhas been given to enhance their sensitivity. Available optical materials providing a Faraday effect largeenough to be seriously considered for sensitive measuremellts of small magnetic field can be classified intwo groups. In one group are the paramagnetic anddiamagnetic doped glasses. In the other class are therare earth iron …     

一种新型MEMS温度传感器的设计

本文提出了一种新型的多层梁结构的电容式温度传感器.传感器结构部分是由导体(或半导体)/介质层/导体(或半导体)组成的可变电容器.电容的上下极板分别为金属和衬底硅,中间介质层为二氧化硅层.与传统的温度传感器相比,这种结构的测温范围较宽.文中,应用多层梁理论模型分析了传感器的结构,并利用ANSYS有限元分析对模型进行了验证.当多层梁材料参数已知的情况下,选用大面积,低厚度,能够最大限度的提高传感器性能.