Measurement Science Department, Idaho National Laboratory, 1955 N Fremont Avenue, Idaho Falls, ID 83415, USA.
Department of Electrical and Computer Engineering, Boise State University, Boise, ID 83725, USA.
Sensors (Basel). 2021 Dec 8;21(24):8193. doi: 10.3390/s21248193.
Neutron and gamma irradiation is known to compact silica, resulting in macroscopic changes in refractive index (RI) and geometric structure. The change in RI and linear compaction in a radiation environment is caused by three well-known mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced compaction (RIC), and (iii) radiation-induced emission (RIE). These macroscopic changes induce errors in monitoring physical parameters such as temperature, pressure, and strain in optical fiber-based sensors, which limit their application in radiation environments. We present a cascaded Fabry-Perot interferometer (FPI) technique to measure macroscopic properties, such as radiation-induced change in RI and length compaction in real time to actively account for sensor drift. The proposed cascaded FPI consists of two cavities: the first cavity is an air cavity, and the second is a silica cavity. The length compaction from the air cavity is used to deduce the RI change within the silica cavity. We utilize fast Fourier transform (FFT) algorithm and two bandpass filters for the signal extraction of each cavity. Inclusion of such a simple cascaded FPI structure will enable accurate determination of physical parameters under the test.
中子和伽马辐照已知可使二氧化硅致密化，导致折射率 (RI) 和几何结构的宏观变化。在辐射环境中 RI 的变化和线性压实是由三个众所周知的机制引起的：(i) 辐射诱导衰减 (RIA)、(ii) 辐射诱导压实 (RIC) 和 (iii) 辐射诱导发射 (RIE)。这些宏观变化会导致光纤传感器中监测温度、压力和应变等物理参数的误差，从而限制了它们在辐射环境中的应用。我们提出了一种级联法布里-珀罗干涉仪 (FPI) 技术，以实时测量 RI 的辐射诱导变化和长度压实等宏观特性，主动补偿传感器漂移。所提出的级联 FPI 由两个腔组成：第一个腔是空气腔，第二个腔是二氧化硅腔。空气腔的长度压缩用于推断二氧化硅腔内的 RI 变化。我们利用快速傅里叶变换 (FFT) 算法和两个带通滤波器对每个腔的信号进行提取。包含这样一个简单的级联 FPI 结构将能够准确确定测试下的物理参数。
