In this blog post, we'll take a deep dive into the key performance tests for fiber optic patch cords — polarity verification, insertion loss and return loss measurement, 3D interferometric endface metrology, and endface inspection — along with the relevant standards, equipment . In this blog post, we'll take a deep dive into the key performance tests for fiber optic patch cords — polarity verification, insertion loss and return loss measurement, 3D interferometric endface metrology, and endface inspection — along with the relevant standards, equipment . In this blog post, we'll take a deep dive into the key performance tests for fiber optic patch cords — polarity verification, insertion loss and return loss measurement, 3D interferometric endface metrology, and endface inspection — along with the relevant standards, equipment, methodologies, and. 3D endface testing is a critical procedure to ensure the performance of optical fiber connectors. During fiber patch cord production, manufacturers use 3D interferometers to inspect connector endfaces and strictly control dimensional parameters. Their performance directly impacts signal quality, insertion loss (IL), and return loss (RL).