This part of IEC 62572 deals with reliability assessment of laser modules used for telecommunication. The aim of this standard is – to establish a standard method of assessing the reliability of laser modules in order to minimize risks and to promote product development and reliability; – to establish means by which the distribution of failures with time can be determined. This should enable the determination of equipment failure rates for specified end of life criteria. In addition, guidance is given in IEC TR 62572-2.