OTDR
OTDR stands for Optical Time Domain Reflectometer. It is a device used in optical fiber communication to characterize and troubleshoot optical fiber links.
The OTDR works by injecting a short pulse of light into the fiber and then measuring the reflected light or backscattered light as it travels along the fiber. By analyzing the backscattered light, the OTDR can determine various parameters of the fiber link, such as the fiber length, attenuation, and the location and magnitude of any splice points, connectors, or breaks in the fiber.