Three-core fiber-based shape-sensing application.

By using specially designed three-core fiber, a microstructured light-pattern generator for sensing 3-D shapes has been demonstrated. The square or hexagon grid-interferometric fringe pattern formed by the fiber-optic interferometric grid generator is projected onto an object's surface. The deformed grid pattern containing information of the object's surface topography is captured by a CCD camera and is analyzed using 2-D Fourier transforming profilometry. The use of the fiber-optic grid-interferogram technique greatly simplifies the holographic interferometry system, and the carrier grid interferogram can be conveniently generated without the use of excessive auxiliary components or sophisticated experimental devices; moreover, the three-core fiber can be used in very narrow places, owing to its small size. Finally, the square or hexagon grid-interferometric fringe pattern provides a data-fusion ability that could further improve the accuracy of the 3-D shape-sensing results.