Development of Magnetic Camera Using Hole Sensor and Magnetic Fluid

在实验基础上，组装了安装在XYZ三轴级的分辨率约为100 μ m的三维扫描高灵敏度孔传感器，用于铁磁材料的非接触测量。以S45C钢板为样品，在外磁场中测量了其周围的磁性分布，并考虑了用非接触测量方法实现铁磁可视化的可能性。因此，常规技术很难观察到S45C样品的三维形状，如样品深度的变化。此外，虽然可以检测铁磁性样品，但发现样品中穿透孔的检测灵敏度随着样品与传感器距离的增加而迅速下降。接下来，将钢板（S45C）和磁流体作为磁透镜，设置在传感器的后面，期望它能将磁通量聚焦到传感器上。将几种不同形状的磁透镜应用于检测时，表明了检测铁磁材料三维形状变化的可能性。另一方面，用这种磁透镜对铁磁性材料的可视化测量进行了有限元分析，并没有得到与实验结果数据相似的趋势。为了优化磁透镜形状，实现磁性材料的可视化，需要充分考虑外磁场波动等多种条件。利用这一研究成果，有望开发出可视化埋设铁磁材料的技术。

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.