Dynamic strain measurement method and dynamic strain measurement device based on Brillouin phase shift detection

The invention discloses a dynamic strain measurement method based on Brillouin phase shift detection. The dynamic strain measurement method comprises the following steps of dividing laser signals into two paths; after one path of signals are subjected to broadband frequency shift, generating optical heterodyne to detect local oscillator light wave and detection signal light wave, and synchronously injecting the local oscillator light wave and the detection signal light wave into a sensor fiber; after spectrum broadening, causing the other path of laser signals and a pulse generator to generate broadband Brillouin pulse pumping light wave, and injecting the broadband Brillouin pulse pumping light wave into the sensor fiber; setting a modulator to drive a voltage waveform to introduce linear chrip so as to obtain broadband laser, which is approximate to a rectangular spectrum, and extending a linear region with the Brillouin phase shift of the sensor fiber; carrying out coherent detection on the local oscillator light wave and the detection signal light wave through coherent demodulation of a beat frequency signal and a radio frequency signal which are generated by photovoltaic conversion so as to obtain the Brillouin phase shift of the detection signal light wave; demodulating information of a strain signal of the sensor fiber. The dynamic strain measurement method has the advantages that the signal to noise ratio is improved, the dynamic strain measurement range is increased and the detection speed is improved. The invention further discloses a dynamic strain measurement device based on the Brillouin phase shift detection.