This part of IEC 61290 applies to optical fibre amplifiers (OFAs) using active fibres, containing rare-earth dopants, presently commercially available. The object of this International Standard is to establish uniform requirements for accurate and reliable measurements, by means of the electrical spectrum analyzer test method, of the following OFA parameters, as defined in clause 3 of IEC 61291-1: a) maximum reflectance tolerable at input b) maximum reflectance tolerable at output c) maximum reflectance tolerance at input and output A measurement accuracy for reflectance tolerance of /- 0,5 dB should be attainable with this method. The present test method uses the noise figure as the measure of the "tolerance" against reflectance at each port of the OFA. This is because the (total) noise figure of the FOA may significantly degrade due to the multiple-interference if reflectance at one or both of each OFA port exists.