Overview
IEC 60793-1-22:2024 - "Optical fibres - Part 1-22: Measurement methods and test procedures - Length measurement" defines uniform requirements and methods for determining the length and elongation of optical fibre, typically within cable constructions. Accurate fibre length is a fundamental parameter for evaluating transmission characteristics such as optical loss, bandwidth, and overall link performance. The standard describes multiple measurement techniques, required apparatus, sampling and specimen handling, calibration, calculations and reporting of results.
Key topics and requirements
- Measurement methods: The standard documents several principal methods:
- Method A – Delay measuring (time-of-flight techniques)
- Method B – Backscattering (OTDR-style techniques and variants)
- Method C – Fibre elongation (optical measurement of elongation)
- Method D – Mechanical length (physical/mechanical measurement)
- Method E – Phase shift (frequency/phase based measurement)
- Annex F (informative) - Brillouin frequency shift test method for distributed strain/length information
- Apparatus and calibration: Normative requirements for test equipment (sources, detectors, modulators, OTDR-like instruments), launch/receive conditions, and calibration procedures to ensure traceable, repeatable length measurements.
- Sampling and specimens: Guidance on specimen selection, sample preparation, and how to handle fibre within cables for representative measurement.
- Procedures, calculations and results: Defined test procedures, formulas for converting measured quantities to physical length (including use of group index), uncertainty considerations, and standardized reporting/specification information.
Practical applications and users
- Who uses it: fibre manufacturers, cable assemblers, test laboratories, network installers, quality assurance teams, R&D groups, and standards bodies.
- Typical applications:
- Factory acceptance and quality control of fibre and cables (verify length and elongation under load)
- Field verification of installed fibre links and splice/cable sections using OTDR/backscatter methods
- R&D and component characterization where precise length or group-index-dependent measurements are required
- Pulled-cable monitoring and strain assessment when combined with Brillouin techniques
Related standards
- IEC 60793 series (Optical fibres) - this part complements general optical fibre specifications and measurement guidance across the IEC 60793 family.
- Users should consult other IEC documents in the optical fibre series for linked requirements (terminology, optical loss, mechanical tests).
This standard is essential for anyone needing robust, repeatable optical fibre length measurement, ensuring consistent test methods, clear reporting and interoperability across manufacturing and field testing workflows.
Open preview (PDF)Optical fibres - Part 1-22: Measurement methods and test procedures - Length measurement
