Abstract: Object--to increase versatility by way of providing for the possibility of measuring losses in any of the i-th light-guides out of an arbitrary number of lightguides spliced so as to accommodate minimal air gaps, and at the joint between the (i-1)th and ith lightguides spliced without an air gap (ith joint), which is ensured by making successive measurements of the energy of reflected pulses from the energy and total power of the components of a radiation pulse from the end faces of the last and intermediate lightguides and their spliced end faces, and measuring optical losses from methematical formulas.