IEC 60793-49:2018仅适用于多模、渐变折射率玻璃芯（A1类）光纤。该测试方法通常用于生产和研究设施，但在现场不容易完成。？本文描述了一种用于表征渐变折射率多模光纤的模态结构的方法。该信息对于评估光纤的带宽性能是有用的，特别是当光纤旨在支持一系列发射条件时，例如由标准化激光发射器产生的发射条件。这第三版取消并取代了2006年出版的第二版。本版构成技术修订版。与上一版相比，此版本包括以下重大技术变更: a)通过填补一些遗漏来更好地与原始意图保持一致，从而提高测量的严谨性；b)具有较小差模延迟（和较高模态带宽）的光纤的测量，例如IEC 60793-2-10的A1a.3型光纤？用于构造OM4性能类别电缆；关于指定探测器振幅和时间响应、样本展开条件、四象限扫描以及用于计算带宽的径向位置均匀性的新要求。 关键词:渐变折射率多模光纤的模态结构，带宽性能

IEC 60793-49:2018 applies only to multimode, graded-index glass-core (category A1) fibres. The test method is commonly used in production and research facilities, but is not easily accomplished in the field.？This document describes a method for characterizing the modal structure of a graded-index multimode fibre. This information is useful for assessing the bandwidth performance of a fibre especially when the fibre is intended to support a range of launch conditions, for example, those produced by standardized laser transmitters. This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) better alignment with original intent by filling some omissions and therefore improving measurement rigor;
b) the measurement of fibres with smaller differential mode delay (and higher modal bandwidth) such as type A1a.3 fibres of IEC 60793-2-10？that are used in constructing OM4 performance category cables; new requirements on specifying detector amplitude and temporal response, specimen deployment conditions, four-quadrant scanning, and uniformity of radial locations for calculating bandwidth.
Keywords: modal structure of a graded-index multimode fibre, bandwidth performance