Fluid Interface Position Optical Sensor

Sandia National Laboratories has developed a continuously monitoring fluid interface optical sensor.The method of determining the liquid level through a single immersed optical wave guide allows for a simple and mobile solution to fluid monitoring systems.Current technologies use monitored floating devices and require mechanical or magnetic coupling, which can pose problems for mobility and hazardous fluids.Current technologies employ a non-contact method for sensing transparency of liquid which lack the precision and safety of a single optical waveguide method.

The fiber optic technology of this Sandia inventions utilizes the principle of dual-fluorescence, where a primary and secondary fiber are used to compare emitted to absorbed light in the system and calculate the position of the interface between opaque and clear fluids.


  • Mobile and simplistic
  • No moving parts
  • Continuous monitoring
  • Safe for use with flammable or hazardous liquid
  • Can operate over a wide range of wavelengths
  • Response wave shape can be adjusted to provide more controlled measurements

Applications and Industries

  • Measurements of hazardous materials or contaminations
  • Crude oil levels
  • Biofuels
  • Wastewater treatment
Technology ID

US Patent# 7,049,622



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