| 摘要 |
<p>An interferometer used as a rotation sensor is constructed using a strand of optical fiber (112), a portion of which is formed into a sensing loop (114). A pair of lightwaves (W1, W2) are caused to counterpropagate in the sensing loop (114) and are combined to form an optical output signal that has an intensity that varies in accordance with the difference in the phases of the two counterpropagating lightwaves (W1, W2). A phase modulator (192) is positioned on the optical fiber (112) in the sensing loop (114) at a location such that the two counterpropagating lightwaves (W1, W2) are modulated approximately 180 DEG out of phase. The time-varying phase modulation causes a time-varying phase difference ( DELTA PHI M(t)) that is combined with a rotationally-induced Sagnac effect phase to provide a total phase difference that is detected by a photodetector (160). The photodetector (160) provides an electrical output signal this is differentiated to provide a differentiated output signal (520, 450, 460) that has zero-crossings (H min , L min ) that correspond to maxima and minima of the electrical output signal. The time intervals ( DELTA t1 min ) between selected zero-crossings (H min , L min ) are measured and the rotationally-induced phase difference ( DELTA PHI R) caused by the Sagnac effect is calculated from the measured time intervals ( DELTA t1 min ) The rotation rate (Q) is then calculated from the Sagnac phase difference ( DELTA PHI R).</p> |
