| 摘要 |
<p>Polarised light is applied for the detection of acoustic waves and/or temperature or magnetic field changes, to the input end (5) of an optical sensor (1) for transmission therethrough. A path length difference is produced between orthogonal components of the polarised light at the output end of the optical sensor (1), and path length optical compensation means (4) is optically coupled to and so oriented with respect to the input end or output end of the sensor, that the path length difference between the orthogonally polarised components transmitted through the compensator means (4) and the corresponding path length difference in the optical sensor (1) are mutually opposite, thereby reducing the noise content of an output signal derived from the arrangement and fed to polarisation analyser means (3) for producing an indication of structural changes which have occurred in the optical sensor. </p> |
