| 摘要 |
PURPOSE: To measure spectral attenuation in an optical waveguide fiber quickly at a low cost by using an optical time domain reflectometer(OTDR), measuring the spectral damping for a plurality of wavelengths over a certain selected range, and thereby preparing the characteristic curve. CONSTITUTION: The light used should have a wavelength range from 700 to 2000nm as are currently used. If three wavelengths are to be selected, they should preferably be 1310, 1410, and 1550nm. The OTDR used should have an OTDR accuracy of around±0.003db/km which is enough to meet the specified tolerance±0.01db/km. The OTDR 4 is furnished with three lasers 2 having respective working wavelengths 1301, 1410, and 1550nm, and selection of laser 2 is made by a switch 6 while a switch 8 selects the incident end, so that a laser beam 17 is put incident to a fiber end 13 or 15. The reflected light 11 by the fiber 10 is sensed to obtain an OTDR trace, which is subjected to an analysis so that the spectral damping in the optical path is determined.
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