Spectral Multiplexing of Fiber Bragg Grating Sensors for Low-Power Optical Sensor Networks

在大型复杂结构系统的整个使用寿命期间，监测其结构完整性和性能非常重要。在役监控可以提高结构的安全性，减少维修停机时间。这项研究的目的是推导、实现和演示一种低功耗、基于光纤的应变传感器网络，该网络可以扩展到大量传感器，并应用于大型机械和航空航天结构系统的高速测试。低功耗、高数据采集率的传感器网络将针对复合材料结构的两个关键应用进行评估。首先，用于事故生存能力分析的复合材料汽车结构的碰撞测试将使人们更好地了解这些材料在碰撞过程中的行为和吸收能量的方式。在汽车结构中实施具有大量传感器的传感器网络将允许详细分析材料在碰撞过程中的动态失效。第二，传感器网络将应用于复合材料机体结构的雷击测试。由于复合材料固有的低导电性，雷击给飞机结构中的碳基复合材料带来了很大的问题，当转换后的雷电电磁能量传播到材料中时，会导致材料的严重破坏。高密度传感器网络将允许在雷击特性和由此造成的材料损坏之间进行详细的关联。基于对光纤布拉格光栅传感器的光谱特性的测量，我们将推出并测试一种全新的多路复用光纤布拉格光栅传感器的方法。这种多路复用策略可以扩展到大量传感器和高速数据处理，从而能够使用单个低带宽、低功率、低成本的激光光源对大量布拉格光栅传感器进行多路复用。基于组合形状轮廓线和波分复用器，并结合传感器网络响应的先验知识以提高精度，将推导出一种用于在高度复用的光纤布拉格光栅传感器网络中识别和测量传感器数据的算法。这项研究的结果将是光纤布拉格光栅传感器网络的多路复用能力，其功率要求比当前系统低几个数量级，使未来的光纤布拉格光栅传感器网络能够在无线传感平台上使用。

It is important to monitor the structural integrity and performance of large, complex structural systems throughout their service life. In-service monitoring can increase the safety of the structure and reduce downtimes for repairs. The aim of this research is to derive, implement and demonstrate a low-power, optical fiber based, strain sensor network that can be scaled up to a large number of sensors and applied for high-speed testing of large mechanical and aerospace structural systems. The low-power, high data acquisition rate sensor network will be evaluated for two critical applications of composite structures. First, crash-testing of composite automotive structures for accident survivability analysis will better enable the understanding of how these materials behave and absorb energy during a crash. The implementation of the sensor network with a large number of sensors in the automotive structure will permit a detailed analysis of the dynamic failure of the materials during the crash. Second, the sensor network will be applied to lightning strike testing of composite airframe structures. Lightning strikes pose a large problem for carbon composite materials in aircraft structures due to the inherent low conductivity of composite materials, leading to significant material damage as the converted lightning electromagnetic energy propagates through the material. The high-density sensor network will permit a detailed correlation between the lightning strike properties and the resulting material damage. A fundamentally new method for multiplexing fiber Bragg grating sensors based on the measurement of their individual spectral properties will be derived and tested. This multiplexing strategy can be scaled to both a large number of sensors and high-speed data processing, enabling the capability to multiplex a large number of Bragg grating sensors using a single low-bandwidth, low-power, low-cost laser source. An algorithm for sensor data identification and measurement in highly multiplexed fiber Bragg grating sensor networks will be derived based on combined shape profile division multiplexing and wavelength division multiplexing, while incorporating prior knowledge of the sensor network responses for increased accuracy. The outcome of this research would be fiber Bragg grating sensor network multiplexing capabilities with power requirements orders of magnitude less than current systems, enabling future fiber Bragg grating sensor networks on wireless sensing platforms.