| 摘要 |
First and second backscattered optical signals, processed in order to obtain first and second phase signals respectively, are received from first and second sensors (e.g. 302 and 304). The first and second phase signals, which may be directed towards a coherent detection system (e.g. 316 and 318), are used to infer an additional phase signal which is unrecoverable from the first phase signal alone. A strain measurement signal is constructed using the first phase signal and the additional phase signal. The phase signals may be processed using phase unwrapping which may employ an a priori phase signal. Independent claims and embodiments are included in which the first and second sensors (e.g. 302 and 304) have different phase sensitivities. Further independent claims are included in which measurement signals are made in contiguous time intervals. The saturation of the first and second unwrapped phase signals may also be measured. |
