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磁光涡流成像检测装置可实现精细表面下细小缺陷探测。在该装置中,通过物体表面上方的交流激励线圈实现传统的涡流感应,涡流所感应的磁场由法拉第效应来检测。为了实现表面下缺陷的检测目标,激光穿过安放在激励线圈中的特殊的磁光晶体,激光偏振方向在晶体中的旋转大小取决于检测区域磁场的大小,缺陷将使检测区域磁场分量发生变化并使偏振光的旋转角发生相应变化,通过一光学装置转化成“明”或“暗”图像,该光学装置由传统的显微镜、照明系统、偏振器和CCD图像传感器组成。给出了初步的实验探测结果。
Magneto-vortex imaging detection device can achieve fine surface defects detection. In this device, the traditional eddy current induction is realized by the AC excitation coil above the surface of the object, and the magnetic field induced by the eddy current is detected by the Faraday effect. In order to achieve the detection target of subsurface defects, the laser passes through the special magneto-optical crystal placed in the excitation coil. The rotation of the laser polarization direction in the crystal depends on the size of the magnetic field in the detection area. The defect changes the magnetic field component in the detection area And the angle of rotation of the polarized light is changed accordingly and converted into “bright” or “dark” images by an optical device consisting of a conventional microscope, illumination system, polarizer and CCD image sensor. The preliminary experimental results are given.