Hybrid FOSS (HyFOSS)

Hybrid FOSS (HyFOSS)

The HyFOSS technique employs conventional continuous grating fibers and then overlays sections every 3 or 4 feet with 'strong' gratings that can be sampled at higher rates. The new and stronger gratings can be sampled at rates up to 5,000 hertz (Hz), while the continuous grating sections continue to be sampled at the lower 100-Hz rate. This technique enables higher spatial resolution at specific targets without sacrificing resolution in other areas. The ultimate goal is to achieve sampling rates up to 20 kHz. This increased sampling capability would allow structural features related to high-frequency shock and/or vibration to be captured.

Work to date: The team began investigating the technique in early 2013 after a request from NASA's Kennedy Space Center to investigate the development effort required to increase the sample rate from 100 Hz to more than 20 kHz. To date, the OFDR technology does not have the capability to achieve these higher sample rates, though the possibility of fusing Wavelength Division Multiplexing (WDM) is feasible yet with limited spatial resolution. Combining the best of OFDR and WDM technologies into new hardware that utilizes the same optical fiber would allow for high spatial resolution with lower sample rates in addition to the ability to obtain high sample rates at strategically spaced points along the fiber.

Looking ahead: Researchers are investigating a 40-foot fiber strand embedded with the new technology in the laboratory environment. The Armstrong team also is investigating the possibilities of pushing the overall sample rate to 20 kHz.

Benefits

 More measurements: Offers higher sampling rates (up to 5 kHz) for specific portions of the fiber

 Fast processing: Collects data at various resolutions without sacrificing speed

Applications

 Aeronautics and launch vehicles

 Fiber Optic Sensing

Armstrong's portfolio of Fiber Optic Sensing System (FOSS) technologies offers unparalleled options for high-resolution sensing in applications that require a unique combination of high-powered processing and lightweight, flexible, and robust sensors. The system measures real-time strain, which can be used to determine two-dimensional and three-dimensional shape, temperature, liquid level, pressure, and loads, alone or in combination. Initially developed to monitor aircraft structures in flight, the system's capabilities open up myriad new applications for fiber optics-not just in aerospace but also for civil structures, transportation, oil and gas, medical, and many more industries.

The Armstrong approach employs fiber Bragg grating (FBG) sensors, optical frequency domain reflectometry (OFDR) sensing, and ultra-efficient algo-rithms (100 samples/second). Engineers are continually seeking new ways of looking at information and determining what is important. Armstrong's FOSS technologies focus on critical research needs. Whether it is used to determine shape, stress, temperature, pressure, strength, operational load, or liquid level, this technology offers ultra-fast, reliable measurements.