The three standard methods for testing fiber optic cabling are a visible light source, power meter and light source, and optical time domain reflectometer (OTDR). The second reason is. Fiber optic testing ensures the performance and reliability of fiber optic networks. By allowing the user to perform optical measurements without terminating, which requires additional equipment and procedures, test. When you build or upgrade a fiber network, the same four words pop up everywhere— fiber optic (bare fiber), pigtail, patch cord, optical cable. They're related, but they are not interchangeable. Mixing them up drives costs higher, increases loss, and slows your rollout.