Remote magnetostrictive position sensors interrogated by fiber Bragg gratings

We developed position sensors using optical fibers containing Bragg gratings and materials having giant magnetostriction to be used in remote locations. They consisted of one grating attached to a small piece of magnetostrictive material that is displaced inside a known magnetic field gradient. The changes in the magnetic field affect the length of the material which changes the wavelength reflected by the grating thereby, indicating its position. The measurement can be made remotely not needing electrical cables or power sources at the measurement site. In addition, the position is assessed without physical contact with the moving part.