| 摘要 |
<p>A temperature sensor comprises a single-mode all-fibre Michelson interferometer (2, 4-8). The interferometer includes a bi-directional coupler (4) and signal and reference fibers (5, 6) having mirrored ends (7). These two fibers (5, 6) are of unequal lengths to provide an optical path length in-balance and the signal fibre (5) has a metal temperature sensing probe (11) at its mirrored end. The injection current of a laser light source (1) for the interferometer is modulated with a ramping signal so that a linearly moving interference pattern is produced at the output (8) by mixing of the reflected beams propagated in the signal and reference fibers (5, 6). The interference pattern is monitored by a photodetector (9) and electronic circuitry processes the output of the photodetector to determine the optical phase shift between the reflect beams in the signal and reference fibers, which phase shift is dependent on expansion and contraction of the signal fibre with respect to the reference fibre and is therefore related to the temperature at the sensing probe (11). </p> |
