A Fiber Bragg Gratings(FBG) have been used as a sensor head for measurement of temperature and static strain. However, a standard FBG sensor, which is constructed on single-mode fiber, cannot simultaneously measure both temperature and static strain since the sensor has cross-sensitivity between them. The cross-sensitivity problem can be solved by using an FBG constructed on a polarization maintaining fiber(PM-FBG) instead of a standard FBG. In this paper, we report improvement on the sensing resolution for the simultaneous measurement of temperature and static strain. An Fabry-Perot interferometer constructed with PM-FBG(PM-FBG-FPI) is introduced as a sensor head. The fine structure of an PM-FBG-FPI reflection spectrum enables high resolution detection of wavelength shifts. The resulting high resolution measurement is demonstrated experimentally.
To develop an optical scanning device, the magnetostrictive alloy thin films were prepared on silicon wafer and polyimide substrate by d.c. magnetoron sputtering process. The TbFe1.8 film shows a giant positive magnetostriction of about 1200 ppm at 5 kOe, whereas the SmFe2.5 shows a giant negative magnetostriction of about 1200 ppm. The magnetostrictive alloy thin films device showed reproducibility below 5 kOe of magnetic field.
Giant magnetostrictive (GM) composite materials with high corrosion resistance and high electrical resistivity were developed. Magnetostriction of the composite material prepared under magnetic field at 19 kOe was about 880 ppm, and the TbFe2 particle size in the sample was 100-150 μm. Shape anisotropy of the TbFe2 particles induced by compression and magnetic field caused to increase the magnetization and magnetostriction measured for y axis of the composite samples formed with magnetic field. The composite materials showed high resistivity in order to 10-2 Ωm and exhibited in order to 10-2 g hour-1 of corrosion rate. The corrosion rate of the composite samples increased with increasing TbFe2 particle size. The corrosion rate of the composite materials may be affected to volume fraction of the TbFe2 particles exposed area in surface of the composite materials.
Giant magnetostrictive (GM) Tb-Fe-Si films were prepared by magnetron sputtering system. X-ray diffraction pattern showed film samples were in amorphous state. The Tb-Fe-Si film (Tb : Fe : Si = 1 : 2.7 : 0.2) prepared at 373 K showed 30 MPa tensile stresses generated by magnetostriction along in-plane direction. The film sample showed about 4.3 μΩm of electrical resistivity that is about 100 times larger than that of TbFe2 film shown about 5.9 × 10-2 μΩm. The film sample coercivity was 360 Oe. Magnetization of the film sample at 15 kOe of applied magnetic field in parallel direction to the film surface exhibited 81.0 emu/cc. We prepared giant magnetostrictive thin film with higher electrical resistivity than that of TbFe2 thin film.