| 摘要 |
<p>This application relates to methods and apparatus for fibre optic sensing, and distributed acoustic sensing, which can provide information about the environment in which the fibre is deployed, in particular the mechanical impedance of the environment. The method comprises using an interrogator 201 to interrogate an optical fibre 104 coupled to a first element 202 responsive to electromagnetic fields. A varying electric current I, which may be an alternating current, is applied so as to induce a varying force F on said first element. The optical radiation backscattered from within the fibre is analysed to determine a measurement signal indicative of a variation in the backscattered radiation corresponding with said electric current applied. The first element may be a first conductor 202 and the varying current may be supplied to this, or to a second conductor (701 in Figure 7). Alternatively the first element could be a magnetic element (802 in Figure 8). By applying a variable force to the first element, and hence the fibre, the characteristics of the environment can be determined.</p> |
