Patent ID: 7719667

Claim:
Apparatus for determining insertion loss of a mechanical splice between first and second optical fibers ( 34 , 36 ; 44 B, 36 ) made by a connecting device ( 10 ; 40 ) having a portion ( 16 , 20 ) whereby at least a part of light launched into the splice via the first fiber and leaked from the splice can emerge, the apparatus comprising: collecting means (F 1 -F 8 ) configured for collecting at azimuthally symmetrically distributed positions about the axis of symmetry of the portion light which has emerged from said portion, detection means ( 52 ) for detecting the collected light; and means ( 54 ) coupled to the detection means ( 52 ) for measuring power levels of the collected and detected light, the measuring means ( 54 ) being arranged to measure and store a reference power level (P REF ) of light collected while only the first fiber is inserted into the connecting device, and a measured power level (P M ) of light collected while respective ends of the first and second fibers are abutted within the connecting device, and to derive insertion loss of the splice from the measured power level (P M ), the measured reference power level (P REF ) and a calibration factor (C) previously obtained by using the same or substantially identical apparatus and connecting device to measure power level (P′ IN ) of light in a first fiber, a calibration reference power level (P′ REF ) with only the first fiber inserted, and a calibration measured power level (P′ M ) and output power level (P′ F ) of light coupled into a second fiber after such second fiber has been inserted.