Fiber Optic Sensing Technologies Dramatically Improve Structural Health Monitoring and Tank Gauging

Revolutionary FOSS technology offers a wealth of flexible options for a wide variety of applications

AFRC's Fiber Optic Sensing System (FOSS)

NASA's Armstrong Flight Research Center is offering companies that provide sensing solutions for monitoring of structures and asset management of storage tanks a unique opportunity to expand their product line to include unprecedented capabilities.

Known as FOSS (for fiber optic sensing system), NASA's patented, award-winning technology portfolio combines advanced strain sensors and innovative algorithms into a robust package that accurately and cost-effectively monitors a host of critical parameters in real time. These capabilities have significant potential for structural health management and tank gauging applications.

Structural Health Monitoring

  • Shape and Position: Two- and three-dimensional (2D and 3D) displacement, deformation, deflection, twist, tilt, and rotation
  • Stiffness: Bending, torsion, and vibration
  • Operational Loads: Bending moments, shear loads, and torques
  • Strength, Stress, and Fatigue: Pressure, acceleration, and breakage/failure prediction
  • Magnetic Fields: Cracks or other flaws in safety-critical metal structures

Tank Gauging

In addition to monitoring the structure of a tank, FOSS is capable of sensing the tank’s inventory:

  • Amount: Liquid level and evaporation rate
  • Temperature: From cryogenic up to 300 degrees Celsius
  • Stratification: Oil vs. water, sediment vs. liquid, and thermal layers

Manufacturers and end-users of structural and tank sensing solutions can tap into the superior performance of NASA’s FOSS system by licensing either the entire portfolio or only the easy-to-integrate elements that complement their existing products. Many of the FOSS technologies can be applied to OFDR-based systems, WDM-based systems, or both. Detailed information is provided below.

OFDR: optical frequency domain reflectometry
WDM: wavelength division multiplexing

"FOSS is a powerful tool that opens up an entirely new realm of understanding when it comes to testing and validating innovations."
—Allen Parker, NASA Engineer

"FOSS can provide an unprecedented quantity of data, allowing engineers to better monitor and control complex systems and make their designs more efficient and safer."
—Lance Richards, NASA Engineer


The FOSS portfolio offers a range of improvements, depending on which technologies are included:

  • Low Cost: Provides unparalleled capabilities at a drastically reduced cost, enabling broad usage across industries
  • Low Power: Ultra-efficient algorithms and high-speed processing platform allow for rapid processing of data, enabling real-time analysis
  • Fast and Efficient: Processes thousands of measurements using computationally fast algorithms, which also can be used by other fiber optic monitoring systems
  • Adaptive and Accurate: Automatically increases resolution where/when needed across quarter-inch intervals, reducing processing time and data volume
  • Easy to Install: Provides a small, lightweight, flexible sensing platform that can be easily applied to or embedded in a structure
  • Robust and Reliable: Operates effectively in humid—or even liquid—environments and withstands cryogenic temperatures and mechanical vibrations

Potential Applications

Allen ParkerInventor Allen Parker demonstrates the difference between FOSS and conventional strain gauges. The bulky white bundle contains 18 conventional strain gauges. The single yellow fiber optic cable contains hundreds of FOSS sensors. (NASA photo)

FOSS's comprehensive capabilities make it a potential solution to meet an enormous range of monitoring needs.

  • Structural Health and Integrity
    • Buildings and bridges
    • Ocean vessels and aerospace vehicles
    • Oil rigs, platforms, and pipelines
    • Natural gas, petrochemical, and cryogenic fuel storage tanks
    • Turbine blades

  • Tank Gauging
    • Cryogenic liquids (fluid management, layering, temperature)
    • Food products (e.g., milk, wine, drinking water)
    • Grain (temperature, moisture)
    • Oil and natural gas (stratification and acidification)

  • Active Control
    • Truck and automobile frames and suspension
    • Wind turbine blades
    • Aircraft
    • Other flexible structures
    • Robotics

  • Safety and Protection
    • Cargo load balancing
    • Flight testing
    • Refueling drones/unmanned aerial vehicles (UAVs) in flight
    • Monitoring shifts in the earth's crust

  • Non-Destructive Evaluation
    • Identifying and monitoring oil drilling sites
    • Detecting cracks in pipelines
    • Monitoring for damage due to impacts from debris

  • Medical Uses
    • Procedures involving endoscopes and catheters
    • Minimally invasive and robotic surgeries
    • Evaluation of anthropomorphic test figures

For Example...
As a single example of the value FOSS can provide, consider oil and gas drilling applications. The FOSS technology could be incorporated into specialized drill heads to sense drill direction as well as temperature and pressure.

  • Because FOSS accurately determines the drill shape, users can position the drill head exactly as needed.
  • Temperature and pressure indicate the health of the drill.

This type of strain and temperature monitoring could also be applied to sophisticated industrial bore scope usage in drilling and exploration.

Technology Details

FOSS Algorithms Monitor Important Parameters

Can be used with other fiber optic monitoring systems

Strain: Strain is the base parameter that FOSS interprets to determine all other parameters.

Temperature: High temperatures usually have detrimental effect on stored liquids (e.g., water, milk, other beverages).

Liquid Level: It is important to know how much liquid is left in a storage tank before it runs out.

Pressure: Excessive pressure can cause failure and affects safety.

Strength/Stress: Strength determines amount of stress a material can sustain before breaking down. Too much stress can cause fatigue and failure.

Operational Load: All structures have load limitations that need to be monitored.

2D and 3D Shape, Displacement, Deflection, and Tilt: Changes to object's shape or orientation under stress can cause fatigue that can lead to failure/breakage, making this an important safety concern.

Acceleration and Vibrations: These stresses on a structure creates extra wear and tear, accelerating fatigue and failure.

Magnetic Field: Changes in magnetic field may be due to cracks or the presence of addition metals (e.g., weapons).

NASA Armstrong’s FOSS technology revolutionizes fiber optic sensing by using its innovative algorithms to calculate a range of useful parameters—any and all of which can be monitored simultaneously and in real time.

FOSS also couples these cutting-edge algorithms with a high-speed, low-cost processing platform and interrogator to create a single, robust, stand-alone instrumentation system. The system distributes thousands of sensors in a vast network—much like the human body’s nervous system—that provides valuable information.

Licensees can select whichever FOSS algorithms and other technologies meet the needs of their customers. Or they can license the entire portfolio to offer a new line of FOSS-based products.

How It Works

  • Fiber Bragg grating (FBG) sensors are embedded in an optical fiber at intervals as small as 0.25 inches, which is then attached to or integrated into the structure.
  • An innovative, low-cost, temperature-tuned distributed feedback (DFB) laser with no moving parts interrogates the FBG sensors as they respond to changes in optical wavelength resulting from stress or pressure on the structure, sending the data to a processing system.
  • Unique algorithms correlate optical response to displacement data, calculating the shape and movement of the optical fiber (and, by extension, the structure) in real time, without affecting the structure’s intrinsic properties.
  • The system uses these data to calculate and display additional parameters.

Why It Is Better

  • FOSS monitors a plethora of engineering measurements in real time with a single instrumentation system weighing less than 10 pounds.
  • FOSS can discern between liquid and gas states in a tank or other container, providing accurate measurements at 0.25-inch intervals
  • Adaptive spatial resolution features enable faster signal processing and precision measurement only when and where it is needed, saving time and resources. As a result, FOSS lends itself well to long-term bandwidth-limited monitoring of structures that experience few variations but could be vulnerable as anomalies occur (e.g., a bridge stressed by strong wind gusts or an earthquake).


The FOSS portfolio has received more than a dozen awards including:

  • R&D 100 Awards
  • Best of Sensors Expo, Gold Winner, Application Award
  • Tech Briefs Create the Future Award, Winner, Electronics Category
  • TechConnect Innovation Award



FOSS Portfolio Technologies

NASA is seeking companies interested in licensing FOSS patents and launching a commercial product. NASA is also interested in working with companies who have interest in select elements of the portfolio.

Elements of the FOSS system include the following (issued/pending U.S. patents):

  • Real-Time Six Degree of Freedom Shape Sensing Algorithm (16/120,555) — This method for sensing 3D shape and 3D orientation is a highly comprehensive algorithm.
  • Signal Processing via Adaptive Spatial Resolution (9,444,548) — This provides dynamic spatial resolution, optimizing the combination of speed/performance and accuracy.
  • System for Sensing Liquid Levels and Other Aspects of Tank Contents (9,074,921) — This innovation can sense liquids —including cryogenics—as well as stratification within the liquids.
  • Fabricating Robust Optical Fibers for Cryogenic Applications (16/021,499) — This manufacturing process produces moisture-proof fibers with higher accuracy.
  • Integration of Compact, Temperature-Tuned OFDR Laser (62/737,248) — This approach leverages a small laser that has no moving parts and is lower cost than conventional lasers.
  • The algorithms that enable the monitoring of the wide range of engineering parameters, as described above
    • Note: Most FOSS algorithms can be used individually or in combination with other fiber optic monitoring systems.
  • Additional technologies that enhance the functionality of FOSS, including:
    • Smart sensors that can send data to the cloud efficiently (ref. DRC-015-038)
    • An augmented reality system for visualizing the structure/object under the sensor (ref. DRC-016-032)
    • Smart coatings for the FBG sensors to enhance thermal sensing capabilities (ref. DRC-009-013/DRC-010-034)

For More Information about Licensing FOSS

Manufacturers can select whichever FOSS algorithms and other technologies meet the needs of their customers. Or they can license the entire portfolio to offer a new line of FOSS-based products. Contact the Technology Transfer Office at NASA's Armstrong Flight Research Center today to discuss which innovations meet your technical needs and business goals.

Technology Transfer Office
NASA's Armstrong Flight Research Center
PO Box 273, M/S 1100
Edwards, CA 93523-0273
Phone: (661) 276-3368