This part of IEC 60793 establishes uniform requirements for measuring the cut-off wavelength of single-mode optical fibre, thereby assisting in the inspection of fibres and cables for commercial purposes.

This document gives methods for measuring the cut-off wavelength for uncabled or cabled single mode telecom fibre. These procedures apply to all category B and C fibre types.

There are three methods of deployment for measuring the cut-off wavelength:
• method A: cable cut-off using uncabled fibre 22 m long sample, λ cc;
• method B: cable cut-off using cabled fibre 22 m long sample, λ cc;
• method C: fibre cut-off using uncabled fibre 2 m long sample, λ c.

All methods require a reference measurement. There are two reference-scan techniques, either or both of which can be used with all methods:
• bend-reference technique;
• multimode-reference technique using category A1(OM1-OM5) multimode fibre.