激光束偏转法检测金属表面层的缺陷

Detection of Defects under Surface in Metals by OBD Method

本文编程计算了由激光光热效应产生的金属表面的温度分布和泵浦光的调制频率、金属层厚度等的关系，预言检测深度缺陷的能力。用激光光束偏转法检测到表面下不同深处的缺陷，并把面扫描幅值信号以三维象和灰度象显示。

The dependence of the temperature distribution caused by photothermal effect in surface of medal(Al)on modulated frequencies of pump laser and thickness of medal is programmely calculated and the capability of detecting deep defect is predicted. The defects with different depth under surface are detected by the OBD method and three dimensional image and grey level image of amplitude signs with defect information under surface of Al are shown.The amplitude signs are acquired by two demensional scanning pump laser.