ANSI APPROVED
This part of IEC 60793 establishes uniform requirements formeasuring the mode field diameter (MFD) of optical fibre, therebyassisting in the inspection of fibres and cables for commercialpurposes.
The MFD represents a measure of the transverse extent of theelectromagnetic field intensity of the mode in a fibre crosssection, and it is defined from the far-field intensitydistribution as a ratio of integrals known as the Petermann IIdefinition. See equation (1).
The definitions of MFD are strictly related to the measurementconfigurations. The mathematical equivalence of these definitionsresults from transform relationships between measurement resultsobtained by different implementations summarized in figure 1 asfollows:
Four methods are described for measuring MFD:
– method A: direct far-field scan;
– method B: variable aperture in the far field;
– method C: near-field scan;
– method D: bi-directional backscatter using an optical timedomain reflectometer (OTDR).
All four methods apply to all categories of type B single-modefibre shown in IEC 60793- 2 and operating near 1 310 nm or 1 550nm. Method D is not recommended for the measurement of fibres ofunknown type or design.
Information common to all four methods is contained in clauses 1to 8, and information pertaining to each individual method appearsin annexes A, B, C and D, respectively.
- Edition:
- B
- Published:
- 11/01/2003
- Number of Pages:
- 40
- File Size:
- 1 file , 400 KB
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