IEC 60793-1-43:2015

Overview

IEC 60793-1-43:2015 - "Optical fibres - Part 1-43: Measurement methods and test procedures - Numerical aperture measurement" defines a uniform, repeatable method to measure the numerical aperture of optical fibre for commercial inspection and product verification. The standard specifies the reference test method (far-field or NAff) and provides supplementary techniques, sampling rules, apparatus descriptions, calculation procedures and product-specific defaults to support consistent inspection of fibres and cables across manufacturers and test laboratories.

Key topics and requirements

• Scope: Applies to multimode fibre categories A1, A2, A3 and A4; NA is used to predict launching efficiency, splice/joint loss and micro-/macrobending behavior.
• Reference method: Far-field angular radiant intensity measurement (NAff). NA is reported as sin(θ) where θ is the half-angle at which the measured intensity falls to a specified threshold (k% of peak).
• Alternative NA: Theoretical NA (NAth) can be derived from core and cladding refractive-index difference (n1, n2); NAff and NAth should ideally agree.
• Measurement techniques:
  • Technique 1 & 2 - angular scans (detector or rotating fibre geometry);
  • Technique 3 - spatial scan of the far-field pattern;
  • Technique 4 - inverse far-field method (introduced for A4d fibres).
• Apparatus and inputs: Requirements for an incoherent, stable light source with substantially uniform radiance (variations <10%), input optics, fibre end support/alignment, cladding-mode stripper, and output detection systems.
• Sampling and specimen: Defines specimen length, endface preparation and mapping rules (Annex A) to correlate shorter-sample measurements to the reference length.
• Data and calculations: Procedures to determine threshold intensity angle, compute NAff, compare NAff to NAth and provide optional outputs (e.g., full far-field intensity distribution).
• Product-specific defaults: Annex B provides default parameter values and threshold settings for various multimode products to aid consistent inspection.

Applications and users

IEC 60793-1-43 is used when accurate, reproducible numerical aperture data are required:

• Fibre and cable manufacturers (production QA, acceptance testing)
• Independent test laboratories and certification bodies
• R&D and optical component developers assessing launch efficiency and bend sensitivity
• Systems integrators and installers verifying product claims for splice compatibility and performance This standard supports commercial inspection of fibres and cables by defining measurement methods that tie directly to product specifications.

Related standards

• IEC 60793-1-1 (general guidance)
• IEC 60793-1-21 (coating geometry)
• IEC 60793-1-22 (length measurement)
• IEC 60793-1-20 (refractive-index/profile methods referenced for NAth)
• IEC 60793-2-10 / -2-20 / -2-30 / -2-40 (product specifications for A1–A4 multimode fibres)

Keywords: numerical aperture of optical fibre, numerical aperture measurement, inspection of fibres and cables, multimode fibre NA, IEC 60793-1-43.