| 摘要 |
<p>To overcome Kerr effect induced gyro bias in a ring resonator optical gyro, the intensities of the beams travelling in opposite directions around the ring have to be very accurately matched. To achieve this a ring resonator gyro includes a first optical coupler (6), the coupling ratio of which is variable and which divides light from a laser (1) into a first and a second component of generally equal intensity, a second optical coupler (8) which transmits a predetermined proportion of the first component to one input of the ring resonator (15) for transmission around the ring resonator (15) in one sense, and a third optical coupler (9), the coupling ratio of which is variable to couple a variable proportion of the second component to the other input of the ring resonator (15) for transmission around the ring resonator (15) in the opposite sense. The gyro also includes a detector (16) for sensing the intensity of light scattered from the optical ring resonator (15), first varying means periodically varying the coupling ratio of the first coupler (6), sensing means responsive to the output of the detector (16) as the first varying means varies the coupling ratio of the first coupler (6) to sense the difference in intensity in the first and second components travelling around the ring (15), and second varying means to vary the coupling ratio of the third optical coupler (9) and thus the intensity of the second component during alternate periods so that the time averaged intensity of both the first and second components are equal.</p> |
