OFDR optic fiber measurements: Performance limitations

As a part of the PhD research project, an OFDR Rayleigh-based optic fiber sensor is embedded as shown in a beam sample, passing through it 4 times to provide strain measurements along the axis of the fiber during a quasi-static 4-point bending test. Throughout the test, strain data in certain zones-generally where higher strains occur-disappeared and reappeared, without fiber breakage. This phenomenon happened both in loading and unloading phases, and could last minutes.