A repeatable manual polishing technique for correcting endface geometry in fc/pc fiber optic connectors

In fiber optic manufacturing and field maintenance, connector end-face quality is the most critical factor affecting long-term link performance. Automated polishing equipment ensures high repeatability but is economically nonviable for small-scale production, repair labs, and educational settings. Manual polishing offers flexibility, yet its reproducibility has traditionally been limited by operator dependency. This study introduces and validates a highly reproducible manual polishing technique specifically designed to correct apex offset and surface damage in multi-mode FC/PC connectors (OM2 fiber, 50 µm core).

The method combines circular motion with a deliberately biased pressure vector, allowing localized material removal opposite to the measured apex offset. Unlike conventional manual techniques (circular, 8-pattern), this approach compensates for human inconsistency by embedding a corrective vector into the polishing motion itself, rather than relying solely on operator skill. The same trajectory can be repeated with minimal training, as the correction direction is defined geometrically rather than intuitively.

A total of 30 samples were tested. The technique showed excellent reproducibility: in 80% of cases, the median apex offset was reduced from 304 µm to 41 µm — well within the TIA-455-218 specification. For surface-damaged samples, the mean insertion loss dropped from 0.18 dB to 0.041 dB, with similar results across multiple operators and polishing cycles, confirming that the method is robust to operator variations. The process requires no expensive equipment and can be applied to preexisting fixtures, making it accessible for most workshops.

The technique offers clear cost advantages: repairs cost 3–5 times less than full patch cord replacement, and the method can be extended to rework connectors that would otherwise be discarded, significantly reducing material waste. After the correction, mandatory 360° rotation tests reveal residual misalignment, providing an additional quality gate. The method’s simplicity and low entry cost make it suitable for educational curricula and industrial rework stations.