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首页> 外文会议>International Instrumentation Symposium; 20070430-503; Tulsa,OK(US) >Visual detection of the subsurface defects using magneto-optical microscopy
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Visual detection of the subsurface defects using magneto-optical microscopy

机译：使用磁光显微镜目测地下缺陷

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摘要

A visual test method for detecting micro-defects under fine surfaces is described. A new magneto-optical microscope is developed for this work, which has a laser source, CCD camera and exciting coil. A square-pulse current is sent to an exciting coil, which induces eddy-currents in the tested sample surface. The imbedded defect induces a variation of the eddy-current as well the variation of magnetic field, which depends on the local eddy-current. A magneto-optical film is placed above the tested surface. Once the laser beam has reflected from the defect location, the polarization direction of laser will rotate an additional amount within the film. The magnetic field variation that causes the rotation is produced by the imbedded defect. The reflected beam carries an image of the defect, which passes through a polarizer before it reaches the CCD camera. The optical arrangement is such that no light is reflected back to the laser. A pulser supports intermittent square-pulses to exciting coil; the intermittent pulse intensifies eddy currents but reduces the temperature of the exciting coil and sample. In order to get clear image and high resolution, the magneto-optic film and exciting coil are important components for this system ; the material and the arrangement of them are analyzed in this paper. The paper also includes discussion about quantifying the resolution and accuracy of the system with a standard subsurface defect. The system was tested with a 250um subsurface defect, but it is shown that the resolution is 15μm.
机译：描述了一种用于检测精细表面下的微缺陷的视觉测试方法。为此，开发了一种新的磁光显微镜，该显微镜具有激光源，CCD照相机和激励线圈。方波电流被发送到一个励磁线圈，该线圈在被测样品的表面感应出涡流。包埋的缺陷引起涡电流的变化以及磁场的变化，这取决于局部涡电流。磁光膜放置在被测表面上方。一旦激光束从缺陷位置反射，激光的偏振方向将在膜内旋转额外的量。嵌入缺陷会产生引起旋转的磁场变化。反射的光束带有缺陷的图像，该缺陷在到达CCD相机之前先通过偏振器。光学布置使得没有光反射回激光器。脉冲发生器支持间歇方波激励线圈；间歇脉冲会增强涡流，但会降低励磁线圈和样品的温度。为了获得清晰的图像和高分辨率，磁光膜和励磁线圈是该系统的重要组件。本文对它们的材料和排列方式进行了分析。本文还包括有关量化具有标准地下缺陷的系统的分辨率和精度的讨论。测试该系统具有250um的表面缺陷，但显示分辨率为15μm。

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