• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Interrogation of fiber Bragg grating sensors with a tunable laser source.
【24h】

Interrogation of fiber Bragg grating sensors with a tunable laser source.

机译：用可调激光源询问光纤布拉格光栅传感器。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The main objective of this project is to investigate the use of tunable laser for the interrogation of fiber Bragg grating (FBG) sensors and sensor arrays. Two of the most common techniques for wavelength detection: i.e. the direct detection and first derivative techniques are studied. The effect of a particular kind of noise, i.e. the unwanted interferometric signal on the system performance is investigated and methods for enhancing the wavelength detection accuracy are examined.; It is found that the wavelength detection accuracy can be enhanced by using digital filtering and proper wavelength modulation. In a single FBG system that uses the direct detection technique, the wavelength detection error is reduced by using a suitable digital filter after photodetection when the system is working in a scanning mode. The experimental results show that the RMS strain error was about 2 muepsilon in a single FBG sensor when a 51st order FIR digital filter is used when the system is working in a scanning mode. However, when the system is working in a lockin mode, the frequency of unwanted interierometric signals are always in the low frequency region and are therefore difficult to be minimized by use of the low-pass filtering technique.; On the other hand, a system that uses the first derivative technique, the wavelength detection accuracy can be improved by proper modulation of the laser wavelength. I have found that the wavelength detection accuracy depends on both the amplitude of the wavelength modulation and the path difference between the signal wave and other parasitic reflected waves. Generally speaking, the wavelength detection error reduces as the distance between the FBG and the reflection point increases, or when the amplitude of wavelength modulation increases. When the system is working in a scanning mode, the combination of wavelength modulation and digital filtering can reduce the wavelength detection error significantly when the amplitude of wavelength modulation is properly selected.; Computer simulation is carried out to study the performance of a time-division-multiplexed (TDM) tree type FBG array as a function of sensor number amplitude of wavelength modulation and the time delay between adjacent sensing channels. It is found that a 20 FBG array of about 1 muepsilon resolution can be realized by using an optical pulse modulator with extinction ratio of -35 dB for first derivative technique. The maximum wavelength detection error for the direct detection technique pith the same set of parameters is 7 muepsilon.; Experimental study is carried out on a 2-FBG and a 4-FBG TDM array. For the 2-FBG sensor array, measurement accuracy in term of RMS strain errors of 8.77 and 1.2 muepsilon are obtained for the direct detection technique in scanning mode and the first derivative technique in lock-in mode, respectively. For the 4-FBG sensors array, the strain errors are 9.28 muepsilon and 0.74 muepsilon for the direct detection technique in scanning mode and first derivative technique in lock-in mode, respectively. When the first derivative technique is applied to the 4-FBG sensor array working in scanning mode, the RMS strain error, when proper wavelength modulation and digital filtering are applied, is found to be 3.98 muepsilon for a wavelength modulation amplitude of 10 pm.
机译：该项目的主要目的是研究可调谐激光器在光纤布拉格光栅（FBG）传感器和传感器阵列的询问中的使用。研究了两种最常见的波长检测技术：即直接检测和一阶导数技术。研究一种特殊的噪声，即不想要的干涉信号对系统性能的影响，并研究了提高波长检测精度的方法。发现通过使用数字滤波和适当的波长调制可以提高波长检测精度。在使用直接检测技术的单个FBG系统中，当系统在扫描模式下工作时，在光检测后使用合适的数字滤波器可以减少波长检测误差。实验结果表明，当系统在扫描模式下使用51阶FIR数字滤波器时，单个FBG传感器的RMS应变误差约为2 error。但是，当系统在锁定模式下工作时，不需要的干涉测量信号的频率始终在低频区域，因此很难通过使用低通滤波技术将其最小化。另一方面，在使用一阶导数技术的系统中，可以通过适当地调制激光波长来提高波长检测精度。我发现波长检测精度取决于波长调制的幅度以及信号波与其他寄生反射波之间的路径差。一般而言，波长检测误差随着FBG和反射点之间的距离增加或波长调制幅度增加而减小。当系统在扫描模式下工作时，适当选择波长调制的幅度，将波长调制和数字滤波相结合可以显着降低波长检测误差。进行计算机仿真以研究时分复用（TDM）树型FBG阵列的性能与波长调制的传感器数量振幅以及相邻感应通道之间的时间延迟的关系。已经发现，对于一阶导数技术，通过使用消光比为-35dB的光脉冲调制器，可以实现约1μepsilon分辨率的20FBG阵列。直接检测技术的最大波长检测误差在相同的一组参数下为7 mu。在2-FBG和4-FBG TDM阵列上进行了实验研究。对于2-FBG传感器阵列，对于扫描模式下的直接检测技术和锁定模式下的一阶导数技术，分别获得了基于8.77和1.2 eps RMS应变误差的测量精度。对于4-FBG传感器阵列，在扫描模式下的直接检测技术和在锁定模式下的一阶导数技术的应变误差分别为9.28μepsilon和0.74μepsilon。当将一阶导数技术应用于以扫描模式工作的4-FBG传感器阵列时，如果对10 pm的波长调制幅度进行了适当的波长调制和数字滤波，则RMS应变误差为3.98μepsilon。

著录项

  • 作者

    Chan, Julian Chi Chiu.;

  • 作者单位

    Hong Kong Polytechnic University (People's Republic of China).;

  • 授予单位 Hong Kong Polytechnic University (People's Republic of China).;
  • 学科 Engineering Mechanical.; Engineering Materials Science.; Physics Optics.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;工程材料学;光学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号