IEC 61280-1-4:2023 is available as IEC 61280-1-4:2023 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 61280-1-4:2023 establishes the characterization process of the encircled flux measurement method of light sources intended to be used with multimode fibre. This document sets forth a procedure for the collection of two-dimensional fibre optic nearfield greyscale data and subsequent reduction to one-dimensional data expressed as a set of three sampled parametric functions of radius from the fibre’s optical centre. Estimation of the fibre core diameter is not an objective of this document. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- improvement of calibration procedure and calibration traceability;
- improvement of fibre shaker description and requirements;
- addition of pulsed light sources;
- removal of a poorly traceable calibration process using a micro positioner.