| 摘要 |
PCT No. PCT/SE90/00094 Sec. 371 Date Sep. 9, 1991 Sec. 102(e) Date Sep. 9, 1991 PCT Filed Feb. 14, 1990 PCT Pub. No. WO90/10883 PCT Pub. Date Sep. 20, 1990.The present invention relates to a method to use an optical fibre as a sensor. The method involves designing an optical fibre to have a sensor area (12) where the external influence on the fibre that is to be measured, for example pressure or magnetic field, is freely able to influence the fibre. Coherent radiation is then transmitted through the sensor area in several modes. On the receiver side the radiation is split in a detector device (14) into two beams, each including the entire interference pattern created by the transmission in the fibre. After that the beams are plane-polarized in two different directions which are conducted to a signal processing device (9,90) which detects the amplitude and/or frequency content of each beam and from this forms a signal which is a measure of their amplitude and/or frequency relation, which in its turn is a measure of the external influence in the sensor area (12). |
