Development of Magnetic Camera Using Hole Sensor and Magnetic Fluid

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The high sensitivity hole sensor installed in XYZ three axial stage with resolution approximately 100 μ m scaning in three dimensions was assembled on an experimental basis for non-contact measurement of ferromagnetic materials. It measured the magnetic distribution around the steel sheet (the S45C) as a sample in the external magnetic field and the possibility of visualization of the ferromagnet with non- contact measurement was considered. As a result, it was difficult to observe of three dimensional shape of the S45C samples such as change of depth of the samples with conventional technique. In addition, although it is possible to detect the ferromagnetic samples, it was found that detection sensitivity of the penetration hole in the samples decreased rapidly with the increase of distance of the samples and the sensor. Next, the steel sheet (the S45C) and magnetic fluid was as the magnetic lens and was set at the back of the sensor to expect that it could focused the magnetic flux to the sensor. And, when the several types of shape of the magnetic lens was applied to testing, it indicated the possibility to detect the change of three dimensional shape of the ferromagnetic materials. On the other hand, FEM analysis of visualization measurement of the ferromagnetic material by this kind of magnetic lens did not obtain the tendency which is similar call by result experimental data. The further consideration of several conditions such as fluctuation of the external magnetic field sufficiently are needed to optimize of magnetic lens shape and visualize the magnetic materials. Using the results of this study, it is expected to develop the technology which visualizes the burying ferromagnetic materials like in the concrete.