| 摘要 |
<p>A method and apparatus for monitoring the rate of rotation of, for example, a turbine engine shaft (14) during the operation of the engine is described. A chopper (30) extends radially from the shaft (14). Infrared radiation is passed through an input optical fibre (34) having a bevelled end positioned adjacent to the chopper (30) which chops the infrared radiation. The chopped infrared radiation passes into a bevelled end of an output optical fibre (38) which is positioned adjacent to the chopper (30). The rate of rotation of the shaft (14) is detected by monitoring the chopped infrared radiation from the output optical fibre (38). Carbonaceous coatings are formed on the bevelled ends of the optical fibres (34,38) by deposition of oil and combustion products thereon. Although these coatings are opaque to visible light, they are transparent to the infrared radiation used.</p> |
