IEC PAS 60793-1-49:2002

1 INTRODUCTION
   1.1 INTENT
   1.2 SCOPE
   1.3 DEFINITION
2 NORMATIVE REFERENCES
3 APPARATUS
   3.1 OPTICAL SOURCE
   3.2 STABILITY
   3.3 LAUNCH SYSTEM
   3.4 DETECTION SYSTEM
   3.5 COMPUTATIONAL EQUIPMENT
4 SAMPLING AND SPECIMENS
   4.1 TEST SAMPLE
   4.2 SPECIMEN ENDFACES
   4.3 SPECIMEN LENGTH
   4.4 SPECIMEN PACKAGING
   4.5 SPECIMEN POSITIONING
5 PROCEDURE
   5.1 ADJUST AND MEASURE SYSTEM RESPONSE
   5.2 ADJUST DETECTION SYSTEM
   5.3 MEASURE THE TEST SAMPLE
6 CALCULATIONS AND INTERPRETATION OF RESULTS
   6.1 DIFFERENTIAL MODE DELAY (DMD)
   6.2 LENGTH NORMALIZATION
7 DOCUMENTATION
   7.1 REPORT THE FOLLOWING INFORMATION FOR EACH TEST:
   7.2 THE FOLLOWING INFORMATION SHALL BE AVAILABLE UPON REQUEST:
8 SPECIFICATION INFORMATION
ANNEX A (INFORMATIVE) COMPARISON BETWEEN THIS TECHNICAL REPORT
        AND ITU RECOMMENDATIONS
ANNEX B (NORMATIVE) SOURCE SPECTRAL WIDTH LIMITATION
   B.1 LIMITING THE EFFECT OF CHROMATIC DISPERSION ON THE
        VALUE OF DMD
   B.2 CHROMATIC DISPERSION IN MULTIMODE FIBRES
ANNEX C (INFORMATIVE) DISCUSSION OF MEASUREMENT DETAILS

This technical specification describes a method for characterizing the modal structure of a graded-index multimode (category A1) fibre. It is useful for assessing the bandwidth performance of a fibre used with laser sources. A probe spot is scanned across the fibre endface and the optical pulse delay is determined at specified offset positions. The difference in optical pulse delay time between fastest and slowest modes is the Differential Mode Delay.