利用Sagnac干涉原理的分布式光纤传感器是一种可用于长途油气管线侵入、泄漏探测和定位的新技术．为了克服屏蔽和隔离Sagnac光纤环中未用作传感的那一半光纤所带来的屏蔽困难、成本增加等问题，提出一种单轴分布式光纤传感器的方法．其原理是利用一条光纤代替光纤环，并在光纤尾端设置法拉第旋转镜，构成偏振无关Sagnac干涉仪探测和定位管线泄漏．文中详细分析和讨论了该方法的系统光路和探测定位原理．

The pipeline leakage detecting and locating system based on Sagnac interferometer and distributed optical fiber technology has many advantages,such as the long monitoring range and the high precision in fault locating. In the prototype,the non-sensing fiber portion of the Sagnac ring must be shielded to avoid disturbance,which will restrict the application in actual monitoring system. To address this problem,a new optical configuration was put forward in this paper. It adopted one optical fiber line as sensing part instead of the optical fiber ring,and some necessary modifications were made to remove the effect of the fiber birefringence. A theoretical analysis of optical path and locating method were also given in this paper,which demonstrated the feasibility of pipeline intrusion(or leakage) detecting and locating by this system.