DAS System Operation
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Interactive animation showing how Distributed Acoustic Sensing transforms fiber optic cables into seismic sensor arrays
Microscopic imperfections scatter light back to interrogator
Changes in optical path length reveal strain
Each fiber segment acts as independent seismometer
Light travels through the core via total internal reflection. Microscopic imperfections in the glass cause tiny amounts of light to scatter back (Rayleigh backscattering).
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Each vertical line represents a virtual seismometer. Red indicates active detection of seismic waves. DAS can create thousands of these virtual sensors along a single fiber.
The DAS interrogator sends coherent laser pulses down the fiber optic cable at high frequency (typically kHz rates).
Microscopic imperfections in the glass fiber scatter tiny amounts of light back toward the interrogator continuously along the fiber length.
When seismic waves deform the fiber (stretching or compressing), they change the optical path length, creating detectable phase shifts in the backscattered light.
By analyzing backscatter from different fiber segments, the system creates thousands of virtual seismometers along a single cable, providing unprecedented spatial resolution.