| 摘要 |
A sensor responsive to magnetic field strength employs a feedback control loop operating on a piezoelectric stretcher element (13) to maintain a predetermined phase relationship between the optical path lengths of first and second Fabry Perot optical fiber/waveguide interferometer cavities (4, 11) optically in series. The control signal for the loop is derived from monitoring the transmission of the series combination and compensates for changes in optical path length in one of the cavities, the sensor cavity (4), induced by a magnetostrictive stretcher (7). The arrangement is responsive not only to the magnetic field but also to spurious effects resulting from temperature changes and so a reference cavity (5) thermally strapped to the sensor cavity is employed in a similar configuration to provided a second signal for correction purposes. |
