BS EN 60793-1-60:2017

FOREWORD
1 Scope
2 Normative references
3 Terms and definitions
4 Testing conditions
5 Reference test method
6 Specimen
7 Test methods
8 Results
Annex A (informative) - Difference of beat lengths
        by measurement method (phase beat length and
        group beat length)
Annex B (informative) - Correlation between results
        obtained by the two methods (phase beat length
        and group beat length)
Annex C (informative) - Electromagnet for Faraday rotation
Bibliography
Annex ZA (normative) - Normative references to
         international publications with their
         corresponding European publications

Specifies test methods for both the phase beat length, and the group beat length.

This part of IEC60793 defines test methods for both the phase beat length, and the group beat length. These two parameters are defined differently, and will give different results depending on the type of polarization-maintaining (PM) fibre. The phase beat length is the relevant parameter for the fibres ability to maintain a high extinction ratio. This is described in more details in AnnexesA and B.