| 摘要 |
In an optical time domain reflectometry method, in which a plurality of pulses of optical radiation, delayed by known amounts of time relative to one another such that adjacent pulses do not overlap, are launched into an optical fiber (6) of interest and optical radiation backscattered from the fiber (6) is detected to produce electrical output signals the said plurality of pulses have different respective wavelengths and are derived from optical radiation at a preselected wavelength, each of the said pulses having a peak power less than the power at which non-linear effects begin to occur in the said optical fiber (6). The said backscattered optical radiation is processed before detection so as to remove the effect thereon of the relative time delays between the said plurality of pulses.
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