The invention provides a dynamic
strain measurement instrument based on multiple overlapped gratings. The dynamic
strain measurement instrument comprises the multiple overlapped gratings, a
wideband light source, a tunable filter, a positioning coupler, an etalon, a photoelectric
detector and a
demodulation and
control circuit. The multiple overlapped gratings are formed in a way that a plurality of sensing gratings with center wavelengths being distributed at equal intervals are inscribed in an overlapped manner in a same area on a sensing
optical fiber by selecting different phase templates, wherein the center wavelengths of a
fiber Bragg
grating, which are inscribed in the overlapped together, are continuously distributed at equal intervals within a
wavelength scanning range of the tunable filter, so that sensing information of the same
physical quantity to be measured can be continuously obtained for a plurality of times within each
wavelength scanning period, and a
peak value position and
wavelength variation of each sensing
grating in the multiple overlapped gratings, namely reconfigurable original dynamic strain signals, can be recorded. Therefore, the purpose of improving a measurement bandwidth of the dynamic strain signals based on a
grating demodulation system of the tunable filter can be realized. According to the dynamic
strain measurement instrument provided by the invention, the sensed measurement bandwidth of the
fiber Bragg grating based on the tunable filter can be effectively improved, so that the high-speed and high-precision simultaneous measurement requirement of the dynamic strain signals can be met.