Ideal-Photonics's DVS system uses the optical fiber itself as a sensor to feedback the vibration, temperature, stress and other variables at different positions, and achieve precise positioning. At present, this distributed sensing technology has been used in long-distance natural gas and oil transmission leakage monitoring, safety monitoring of large buildings such as bridges, and large-area security systems. We adopted the φ-OTDR technology to build the DVS system, using the direct detection method, and passed the pzt vibration test with the simple structure、 high sensitivity and excellent SNR.
We use φ- OTDR technology has built a 20km optical fiber vibration sensing system, whose theoretical basis is optical fiber backward Rayleigh scattering. The optical path system is shown in the following figure: First, use AOM to modulate the 1550 nm narrow linewidth laser into a pulse light with a pulse width of 100 ns and a repetition rate of 2 kHz. After the pulse light is generated, it is sent to the 20km sensing optical fiber. Due to the backward Rayleigh scattering of the optical fiber, each pulse light will return a section of distributed weak light after passing through the 20km optical fiber. Therefore, an optical ring is added after the AOM to transfer the return light of the optical fiber to another optical fiber and amplify it with EDFA, and then convert it into an electrical signal with a photodetector (PD). Finally, the high-speed FPGA acquisition card is used to collect data.
Distribution Vibration Diagram & one point
vibration time domain diagram