Description: The Naval Research Laboratory (NRL) has developed high accuracy, fiber optic curvature sensor technology allowing for 3D shape sensing. The novel shape sensing technology is based on measuring the differential strain between fiber Bragg grating sensors formed in a multicore fiber (MCF). The NRL fiber optic curvature sensor takes advantage of a novel interrogation technique that overcomes many problems prevalent with other methods such as lead sensitivity and environmental sensitivity of the measurement accuracy. The NRL interrogation technique reduces the sensor drift (equivalent to 1 km-1 over several hours) and can be multiplexed using time and wavelength division multiplexing. The NRL method also provides wide-bandwidth curvature measurement capability (several KHz) over long sensing lengths (several km) and permits small sensor spacing on the order of centimeters. Furthermore, the high measurement resolution achieved with these sensors enables twist and curvature of the optical fiber to be recovered.

Advantages/Features Include:

  • Enhanced accuracy and sensitivity to curvature
  • Able to achieve curvature resolutions ~0.1 km-1/Hz1/2
  • Able to achieve inclination resolution of 0.1° to 0.5° from all-optical inclinometer

Applications Include:

  • Accurate location of UUV and drill heads in oil and gas industry
  • Guiding medical catheters and surgical instruments
  • Monitoring shape changes for morphing aerodynamic control surfaces
  • Monitoring structural health

References:

  • "Ultra-High-Sensitivity Two-Dimensional Bend Sensor" Electronic Letters 42 (9) (2006) 520-522.
  • "Differential Phase Tracking Applied to Bragg Grating in Multi-Core Fibre for High Accuracy Curvature Measurement" Electronic Letters 45 (7) (2006) 390-391.

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