Technology Commercialization Opportunity

Fiber Optic Pressure/Vibration Sensors

Looking to improve current aerospace testing equipment, researchers at NASA Ames have made notable advances in fiber optic pressure and vibration sensor technology. Since virtually any environmental effect can be measured by fiber optic sensors, further research and development is needed to perfect these sensors for an already wide array of potential applications. NASA Ames' current areas of fiber optic study are in acoustics, pressure, stress, and vibration sensors. Commercial feasibility is positive as the volume and variety of applications continue to increase while the cost of optical elements decrease.

Sensor technology utilizes the phase modulation experienced by light propagating through an optical fiber that is exposed to external fields. This phase modulation is interferometrically retrieved and processed to determine a specific external field characteristic, relaying the data at high speeds through the fiber. When configured as an interferometer, any external disturbance that affects the length of the fiber such as strain, pressure, temperature, acoustics, or vibration, causes a phase change in the detected light signal which is measurable by the fiber's electrical unit. Some sensors use a Bragg grating which is contained in a section about 1 cm long and acts as a narrow band filter that detects variation in the optical properties of the fiber. When the fiber is illuminated with an ordinary light source such as an LED, only a narrow band of light will be reflected back from the grating section of the fiber. If a pressure is applied to the grating section of the fiber the grating period changes, and hence the wavelength of the reflected light, which can be measured. This technique isolates the signal from a single point on the fiber for measurement.

Potential Commercial Uses

• Vibration and pressure sensing applications in aeronautical testing of aircraft, helicopters, and rotorcraft. (shown above)
  
• Medical applications such as an artificial voice box where a fiber optic acoustic sensor would be surgically implanted to amplify the vibrations in a patient's throat, doing away with the need for a hand held throat device.
  
• Future high tech security systems may include fiber optic sensor technology. For example, a very unique key could be made in which the door would not unlock unless the key's fiber and lock's code matched exactly. The key's fiber would be virtually undetectable and extremely difficult to duplicate.
  
• A smart system is used to function as the "brains" to a multitude of sensor "arms" that together retrieve, analyze, and relay data from fiber optic sensors used to monitor the environment of a particular location. A potential control unit for this purpose is a modified Automation & Support System for Expert Tele-science (ASSET), also developed at Ames. No work has yet been done on integrating these systems but could be started as a joint R& D project with interested industry partners.
  
• Fiber optic sensors can be utilized in any number of scientific, medical, and field service measuring devices where vibration or pressure detection would be advantageous.

Benefits

• High sensitivity: Fiber optic sensors are extremely sensitive, being able to resolve much less than .01 psi or 1 displacements.
  
• Electrical and optical multiplexing: Multiple sensor heads can be run by one set of electronics, which can themselves be multiplexed to further expand a sensor system.
  
• Immune to electromagnetic interference: Fiber optic light is unaffected by electromagnetic interference and also shows no degradation of results when used underwater or in zero gravity.
  
• Environmental ruggedness to weather and shock: These conditions may cause "noise" but will not damage sensors.
  
• Small, flexible fibers: The optical fiber and sensing head is approximately the size of a human hair and can be configured in arbitrary shapes.
  
• Market driven: The expanding use of fiber optics by telecommunications and other industries continue to reduce the cost of key optical elements.

Options for Commercialization

Key Words

Environmental Sensors, Interferometric Sensors, Intrinsic Fiber Optic Sensors, Pressure Sensors, Vibration Sensors