| 摘要 |
<p>An improved fibre optic sensor for remote flow measurements is disclosed. The sensor consists of two optical fibres (16, 18) placed parallel to each other with a reflective surface (32) (flat or concave) at the end. The fibres and the reflective surface are encased in a flexible tube (24) with an opening (28) in the side of the tube to allow light to be reflected through the opening into a measurement volume of the flow. The cavity created by this opening in the flexible tube is preferably filled with optical cement (34). This surface is polished so that it is flushed with the surface. Light is transmitted to the measurement volume from one of the optical fibres (Transmitting fibre) where it is scattered by scattering particles within this measurement volume. Part of backscatter light is collected by the other fibre (receiving fibre) and the backscatter signal is compared with the transmission signal to determine a Doppler shift.</p> |
