An MPO test set is a specialized optical testing instrument designed to evaluate the integrity and performance of MPO fiber links by measuring insertion loss, return loss, polarity, and continuity across all fibers simultaneously.

These test sets typically include an Optical Loss Test Set (OLTS) with MPO interface adapters, a Visual Fault Locator (VFL), and an MPO-compatible inspection scope for checking endface cleanliness and connector geometry. Advanced models may feature automated fiber mapping, bidirectional testing, and built-in software for generating certification reports.

The test set verifies that each fiber within the MPO array is correctly aligned, properly terminated, and free of defects or contamination.

It also confirms that the polarity scheme—Type A (straight-through), Type B (reversed), or Type C (pair-flipped)—matches the intended design, which is critical for maintaining signal integrity in duplex and parallel transmission systems.

These tools are indispensable for installers and technicians working in high-density environments where MPO links are prevalent, such as hyperscale data centers and enterprise backbone networks.