With the Brillouin OTDR technique temperature changes and stress on a fiber can be accurately localized to within a few meters. Distributed sensing provides direct method of measuring the changes in strain and temperature along the entire length of. Brillouin Optical Time Domain Reflectometry (BOTDR) is a distributed fiber optic strain sensing system, which can detect temporal and spatial changes of external physical parameters at large-scales and on a continuous basis. Nevertheless, there are still many problems in the application. According. Abstract: In this paper, a standard test method of evaluating the measurement performance of distributed sensors such as Brillouin scattering based fiber optic sensors (FOSs) and other long gauge sensors for monitoring cracks is proposed. The performance evaluation of two types of Brillouin. This white paper provides an overview of BOTDR detection and measurement principles and the Brillouin scattering characteristics of Corning's single-mode optical fibers that have enabled engineers to use BOTDR techniques to remotely locate and assess strained fibers in deployed cables in link.