Advanced distributed fiber optic sound sensor DAS

Product Introduction
Advanced Distributed Optical Fiber Sound Sensor (DAS), based on the principle of coherent Rayleigh scattering, uses a single core ordinary single-mode communication optical cable as the sensor, which can obtain real-time temperature and vibration information around any point along the cable. When there is a temperature change or vibration around the optical cable and it reaches a certain threshold range, the analysis system of the fiber optic sound sensor will issue a warning in the first time, accurately locate the location of the event, and notify relevant monitoring personnel.
This DAS adopts a modular design, integrating high-tech such as optoelectronics, hardware, computer, and information processing. It can measure distances up to 50km and has a spatial resolution of up to 2m. It can monitor events within 40m around optical fibers. Using optical fibers as sensors and optical signals as carriers, optical fibers are both sensors and transmission units, not affected by electromagnetic interference, inherently safe, and suitable for working in harsh environments. They have important application value in fields such as pipelines, railways, perimeter security, oil and gas. There have been numerous application cases both domestically and internationally, and practical use has proven that DAS has significant advantages in certain application fields.

measuring principle 
Distributed sound sensor DAS is a distributed fiber optic sensor based on coherent Rayleigh scattering. It utilizes the sensitivity of optical fibers to sound (vibration). When external vibrations act on the sensing fiber, the refractive index and length of the fiber will undergo slight changes due to the bounce light effect, resulting in phase changes of the transmitted signal inside the fiber and changes in light intensity.
The phase change caused by sound waves is very small, so DAS systems usually use highly coherent pulse light sources. Interference occurs between Rayleigh scattering signals within the pulse width region. When external vibrations cause a change in phase, the intensity of the coherent Rayleigh scattering signal at that point will change. By detecting the intensity change of the Rayleigh scattering light signal before and after vibration (differential signal), vibration events can be detected and multiple vibration events can be accurately located simultaneously.

Technical Advantages

• Continuous distributed measurement of temperature and vibration, without measurement blind spots
• Simultaneous detection and accurate localization of multiple events
• Fiber optic is a sensor that combines transmission and sensing
• 50 kilometers of ultra long measurement distance, rich measurement information
• Fast response speed, alarm within 1 second
• Optical signal transmission, completely electrically insulated, resistant to electromagnetic interference
• Inherent safety, suitable for long-term work in flammable and explosive environments
• Stable and reliable measurement with low false alarm rate
• Fiber optic has a long lifespan, up to 30 years without maintenance

Performance Features

• Temperature distance: 50km
• Fast response time: 1s@50km
• High positioning accuracy: 2-50m
• High sensitivity: capable of sensing vibrations within 40m around the optical cable
• Simultaneous monitoring of vibration and temperature
• Fiber optic fault online monitoring function
• User friendly software that provides a visual interface