Rhombic Optical Path Difference Bias Sagnac Interferometric Intrusion Location System

We propose a novel Sagnac interferometric intrusion localization system based on a rhombic optical path differential bias configuration for localization detection of intrusion signals. In contrast to the intricate multipath detection architecture employed in traditional Sagnac intrusion localization systems, the proposed system described in this article achieves comparable results through the utilization of a single detection optical path. This represents an improvement in terms of system simplicity and efficiency. The rhombic optical path differential bias Sagnac intrusion localization system has the advantages of simple structure, low cost, and optimized demodulation method. By combining the spectral analysis of the phase signal with the first-order null-frequency point method and the “Twice-FFT” algorithm, the intrusion location measurement of low- and high-intensity intrusion signals is achieved, respectively. Based on the findings presented in this article, it has been demonstrated that the system put forward in this study effectively achieves localized detection of intrusion signals. Furthermore, it exhibits the potential to possess the capability to discern the specific type of intrusion. According to the results presented in this study, the maximum standard deviation observed for intrusion localization of low-frequency signals is a mere 11 m. In addition, the maximum standard deviation observed for intrusion localization of high-frequency signals does not surpass 20 m.