Skip to Content
Find More Like This
Return to Search

Fiber-Optic Long-Line Position Sensor

Sandia National Laboratories

Contact SNL About This Technology


PDF Document PublicationMarket Sheet (831 KB)

Technology Marketing SummarySandia National Laboratories has developed a side-emitting fiber optic position sensor and method of determining an unknown position of an object by using the sensor.  Non-electrical position sensors like the one developed by Sandia are desirable for use in hazardous environment, e.g., for measuring the liquid level in gasoline or jet fuel tanks.  This sensor is an attractive option because it does not introduce electrical energy, is insensitive to electromagnetic interference, has very few moving parts, and could provide continuous measurements.DescriptionLarge-scale rotary drilling for oil and gas, minerals, and water wells have a need for measuring the depth of drill bits and pipe segments.  Measuring the length of a cable played out is often inaccurate because the cable stretches under heavy loads.  There is a need for a long-range position sensor that is non-contact, simple, inexpensive, reliable, compact, non-electrical, and robust.  These and other features have been achieved in the present Sandia invention. Benefits
  • Sensor does not introduce electrical energy and is insentive to electro-magenetic interference
  • Does not require the use of florescent dopants
  • Can operate over a wide range of wavelengths at a reduced cost
  • Has very few moving parts
  • Provides continuous measurement
Applications and Industries
  • Oil and Gas
  • Minerals
  • Water Wells
  • Fuel Tank Measurement
  • Hazardous Environments
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 7,329,857
Side-emitting fiber optic position sensor
A side-emitting fiber optic position sensor and method of determining an unknown position of an object by using the sensor. In one embodiment, a concentrated beam of light source illuminates the side of a side-emitting fiber optic at an unknown axial position along the fiber's length. Some of this side-illuminated light is in-scattered into the fiber and captured. As the captured light is guided down the fiber, its intensity decreases due to loss from side-emission away from the fiber and from bulk absorption within the fiber. By measuring the intensity of light emitted from one (or both) ends of the fiber with a photodetector(s), the axial position of the light source is determined by comparing the photodetector's signal to a calibrated response curve, look-up table, or by using a mathematical model. Alternatively, the side-emitting fiber is illuminated at one end, while a photodetector measures the intensity of light emitted from the side of the fiber, at an unknown position. As the photodetector moves further away from the illuminated end, the detector's signal strength decreases due to loss from side-emission and/or bulk absorption. As before, the detector's signal is correlated to a unique position along the fiber.
Sandia National Laboratories 02/12/2008
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
Patent# 7,329,857, SD# 10001Prototype - Sandia estimates this technology at a TRL 5. Key elements of the technology have been demonstrated in relevant environments. Available - Various license and partnering options are available. Please contact the Intellectual Property department to discuss.07/08/201103/12/2013

Contact SNL About This Technology

To: Technology Inquiries<>