作为分布式光纤传感器核心技术，光反射仪能够对光纤进行非破坏性检测，获取沿光纤长度的反射率、折射率和偏振态等分布信息来判断光纤链路各类异常“事件”。在一些高端监测领域，例如光纤到户(fiber-to-the-home, FTTH)接入网的故障诊断、大型发电机组和大型变压器内部的热点和形变监测以及大飞机的机翼结构安全监测等应用，对传感器空间分辨率、测量距离等性能提出了非常高的要求。本文总结了光反射仪技术国内外的研究现状，并针对应用需求，回顾了几种实现长距离高空间分辨率光反射仪的关键技术及其在实现更高性能时所面临的技术难点。针对各类技术难点，分别提出三种创新性方案，从三种不同角度加以改善，推动光反射仪技术在分布式传感系统中的应用。

As the core technology of distributed fiber-optic sensing, optical reflectometry may realize the non-destructive measurement at a remote position. It can be used to retrieve the distributed information such as reflectance, refractive index, polarization state along the optical fiber, and to diagnose the irregular “event” on fiber- optic links. For some high-end fields, such as the fault diagnosis on the fiber-to-the-home (FTTH) access network, the deformation monitoring on large generating units and large transformers, and the security monitoring on structures of airplane wings, the requirements on spatial resolution and measurement range of the sensing technologies are very high. In this paper, we summarized the research status on state-of-art optical reflectometry technologies, and reviewed the advances of key technologies on optical reflectometry with ultra-high spatial resolution and long measurement range. We proposed three different methods to improve the performance, and tried to promote their applications on distributed fiber-optic sensing systems.