High-precision Fiber Bragg Grating Research Articles

Design of a high-precision current source system for tunable laser driving

Fiber Bragg Grating (FBG), which is an Optical Fiber Sensor with high sensitivity, light weight, and strong anti-interference ability, can realize the measurement of physical quantities, such as temperature and strain. The sensor network formed by FBG sensors is through wavelength division multiplexing, which greatly reduced the difficulty of sensor wiring. Therefore, FBG sensors are widely used in sensing fields such as aerospace, bridges and tunnels. As a wavelength-modulated Optical Fiber Sensor, FBG’s sensing accuracy depends not only on the performance of the laser, but also on the stability of the driving current. In this paper, a high-precision current source system for laser S7500 modulation drive is designed, with a resolution of output current is higher than 2uA. and the laser S7500 is continuously linearly scanned at 20pm intervals in the wavelength range of 1527nm to 1567nm. The wavelength accuracy of the output optical signal is better than 2pm. The test results prove that the system has the advantages of high modulation speed, good stability and high reliability, and can be applied to high-precision FBG sensor networks.

High-Precision FBG 3-D Force Sensor Based on Spatial Hierarchical Sensing Structure

A 3-D force sensor based on fiber Bragg grating (FBG) is proposed in this article. A spatially layered elastomer structure is designed, and a single-mode fiber inscribed with four FBGs is laid at each place of the structure to realize the 3-D force sensing of the robot and compensate for temperature interference. The principle of FBG sensing and force measurement is investigated to reveal the mapping relationship between the wavelength drift and force of this 3-D force sensor. Based on the finite-element simulation analysis, the FBG package position is optimized, and the sensor prototype is tested. Experimental results show that the linearity of the 3-D force sensor force sensing is good, and its sensitivity is 3.104, 3.077, and 1.890 pm/N. Based on sparrow search algorithm optimization extreme learning machine (SSA-ELM), a nonlinear decoupling algorithm is used to construct the neural network model, and the SSA is used to optimize the model and obtain the best initial weights and thresholds of the network. The maximum I error after decoupling is 1.58%, the maximum II error is 0.93%, and the decoupling training time is 1.44 s. The algorithm can construct the interdimensional coupling relationship of 3-D force more effectively and improve the sensor measurement accuracy. In addition, the sensor has strong resistance to electromagnetic interference and noise, fewer sensitive components, a simple lineup, a small structure and lightweight, and easy processing, and meets the requirements of miniaturization, lightweight, and refinement of multidimensional force sensors for collaborative robots.

Construction and Application of On-Line Roof Separation Monitoring System Based on High-Precision FBG Indicator

Aiming at the existing problems of low efficiency, lagging monitoring results, and poor reliability and accuracy in the present roadway roof separation monitoring system, a high-precision Fiber Bragg Grating (FBG) separation indicator is designed through theoretical analysis, numerical simulation, and laboratory tests—according to the fiber grating sensing principle. Based on the Microsoft. Net platform, C# programming language, and VS2010 integrated development tools, the corresponding on-line monitoring software is developed. On this basis, a real-time on-line roof separation monitoring system is proposed. The high-precision FBG separator was calibrated and tested in the laboratory and results suggested that both the left and right arm demonstrate good sensitivity and linearity with linear fitting coefficient values of 0.9981 and 0.9979, respectively. The monitoring system was successfully applied to roof separation monitoring of the #14301 rail roadway in the Shaqu coal mine. The monitoring results showed that the on-line roof separation monitoring system based on the high-precision FBG separation indicator has the advantages of high precision, good stability, and long-distance signal transmission, which can achieve real-time dynamic monitoring and provides an effective method for long-term on-line monitoring of roadway roof separation.

Design and Experimental Validation of a Fiber Bragg Grating-Enabled Force Sensor With an Ortho-Planar Spring-Based Flexure for Surgical Needle Insertion

This paper presents the development of a novel and high-precision Fiber Bragg Grating (FBG)-based sensor for the measurement of insertion forces during the needle puncture procedure. The proposed sensor mainly comprises two compact orthogonal planar springs connected in a parallel arrangement, one suspended FBG optical fiber and a hand-held sensor frame. Two orthogonal planar springs with curved limbs have been utilized to design the force-sensitive flexure with an excellent linear force-displacement relationship along the axial direction. The employed optical fiber has been arranged along the flexure’s central line, and it is tightly suspended under a pre-tension force with its two ends glued. This two-point pasting configuration can attain improved sensitivity and resolution and avoid the drawbacks of chirping and low repeatability. Finite element modeling (FEM)-enabled simulation has been implemented for design optimization to further advance the sensor sensitivity and performance investigation. The sensor’s axial sensitivity has been increased in the condition when the radial crosstalk decreased. The proposed sensor has been prototyped and calibrated to achieve a high resolution of 1.5mN within [0, 6N] and an excellent linearity with a small linearity error of 0.5%. This design can be conveniently customized to achieve adjustable measurement range and force sensitivity, which has been validated by the further simulation sensor version with a resolution of 4.9mN within [0, 20N]. In-vitro puncture experiments on silicone phantoms, artificial venipuncture simulation module and eggshell membrane, and ex-vivo puncture experiments on porcine liver and porcine aorta have been implemented to validate the effectiveness of the presented sensor design.

Experimental Investigation and Error Analysis of High Precision FBG Displacement Sensor for Structural Health Monitoring

High precision structural displacement monitoring is challenging, but an effective method for structural health monitoring and particularly damage evaluation. In this paper, a high precision fiber Bragg grating (FBG) displacement sensor with embedded spring is developed to monitor structural displacement variation even at very small ranges. The principle of such monitoring is based on the central wavelength shifts in accordance with the displacement between measuring points. Calibration experiments are conducted to examine the performance of the innovative displacement sensor. The result indicates that the sensor has excellent linearity and repeatability, with the sensitivity coefficient being 23.96[Formula: see text]pm/mm, and the static relative error is 4.94% after three loading and unloading cycles. The displacement sensor therefore shows an excellent sensitivity and high precision for application. Moreover, it has been verified that this sensor is suitable and applicable for displacement monitoring in quasi-static experiment of structures.

Fiber optic displacement sensor used in railway turnout contact monitoring system

Railway turnout contact monitoring is very important in high-speed rail operation systems. In order to measure the distance between the sharp rail and the basic rail in a switch system, a wide-range, high-precision fiber Bragg grating (FBG) displacement sensor was designed. Because the distance between the sharp and basic rails is always greater than 14 cm, the measurement range width and accuracy of the proposed sensor system are ensured through the use of a long spring and a beam of constant strength. A differential compensation method is used to eliminate temperature effects. Test results show that the resolution of the proposed sensor is 0.040 mm and the measuring range is 0–170 mm. A field test was also carried out to evaluate the performance of the sensors.

High-precision FBG demodulation using amplitude ratio curve with sharp peak

Abstract For the fiber Bragg grating (FBG) sensor based on the reflection peak position searching demodulation algorithms, a key problem is that the demodulation precision of measurement signal is seriously limited by the full width half maximum (FWHM) of the FBG reflection spectrum. In this paper, in order to overcome this problem and enhance the measurement precision, we proposed a high-precision demodulation method based on amplitude ratio curve to instead of the FBG reflection spectrum, which can increase the sensing precision significantly. In this method, the Bragg wavelength of FBG is modulated periodically with a sinusoidal function to obtain a series of reflection spectra. Then at each wavelength the amplitude ratio between second harmonic frequency component and fundamental frequency component is calculated to create the amplitude ratio curve. Here, we present a comprehensive theoretical analysis and experimental demonstration to verify the advantages of this method. Comparing with the demodulation method based on the FBG reflection spectrum, the average maximum measure error (MME) of Bragg wavelength is reduced from ±1.54 pm to ±0.15 pm, which improved by 10.3 times. In addition, the influence of the modulation amplitude and sampling frequency on demodulation accuracy are also studied in this paper.

High-resolution fiber Bragg grating sensor and its applications of geophysical exploration, seismic observation and marine engineering

With the development of fiber Bragg grating (FBG) and FBG based resonant cavity writing and signal demodulation technique, the measurement precision and frequency bandwidth of FBG sensor continue to be improved. It can highly promote its application in several fields of high precision detection requirements, such as geophysical exploration, seismic observation and marine observation. At present, the development of high-precision and wide bandwidth FBG sensors still face some challenges of key devices and techniques, including high-fineness FBG based resonant and low-noise narrow-linewidth tunable laser, high-precision broadband FBG wavelength demodulation technique, large-scale networking technique and high-sensitivity signal pickup probe design. Firstly, this paper introduces the development of high-precision FBG sensing technique. Secondly, it focuses on the cord devices and key techniques required for high-precision FBG sensing system and their applications in geophysical exploration, seismic observations and ocean observations. Finally, the high-precision FBG sensing technique and its application are prospected. In order to provide references for the development and application of high-precision fiber Bragg grating sensing technology, this paper aims to analyze and summarize some of the core techniques involved in high-precision FBG sensing technique and its application and the key issues that need to be solved.

Design and realization of high precision FBG rain gauge based on triangle cantilever beam and its performance research

A novel fiber Bragg grating (FBG) rain gauge is proposed in this paper to achieve high precision rainfall measurement. One core sensitive FBG, a temperature compensation FBG and a mechanical transition system construct this novel FBG rain gauge. Sensing principle of this FBG rain gauge is explained in detail, and its theoretical calculation model is also established, which shows that the relationship between center wavelength of sensitive FBG and external rainfall has very good linearity. To verify its detection performance, the calibration experiment on one prototype of this FBG rain gauge is carried out. After experiment data analysis, the detection precision of this FBG rain gauge is 15.4 μm which is almost two orders of magnitude higher than that of the existing rainfall measurement device. The experimental data confirm that this FBG rain gauge can achieve rainfall measurement with high precision.

温度实时补偿的高精度光纤光栅压力传感器

温度实时补偿的高精度光纤光栅压力传感器

基于频谱分区的高精度光纤光栅波长解调系统

基于频谱分区的高精度光纤光栅波长解调系统

微型高精度光纤布拉格光栅土压力传感器研究

微型高精度光纤布拉格光栅土压力传感器研究