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传统超声无损检测的工作范围通常在1～10MHz,而声显微镜检测则是一种先进的超声成象方法,其工作频率可及数百兆赫。由于频率较高,故可获得很高的分辨率,在试件中可探出的缺陷远比过去能探出的要小得多。另外。只有几毫米大的试件不能用普通的方法进行无损检测,现在也就可以检验了。实现声显微镜检测的关键是采用聚焦激光束。这种聚焦激光束成为一个小型的逐点超声传感器(接收换能器)。激光器以每秒30幅图象的速率扫描试件的表面,每幅图象包含4万个象点。本文的主题是讨论声显微镜的应用,着重讨论商用激光扫描声显微镜(SLAM)无损检测金属、陶瓷、聚合物及复合材料所获得的效果。
Conventional ultrasonic nondestructive testing usually ranges from 1 to 10 MHz, while acoustic microscopy is an advanced ultrasound imaging method that operates at frequencies up to hundreds of megahertz. Because of the higher frequency, high resolution is achieved, and the probable number of defects detectable in the specimen is much smaller than in the past. In addition. Only a few millimeters large specimens can not be used non-destructive testing methods, and now we can test. The key to achieving acoustic microscopy is the use of focused laser beams. This focused laser beam becomes a small point-by-point ultrasonic sensor (receiver transducer). The laser scans the surface of the specimen at 30 images per second, each image containing 40,000 dots. The subject of this article is to discuss the use of acoustic microscopy focusing on the non-destructive detection of metals, ceramics, polymers and composites by commercial laser scanning acoustic microscopy (SLAM).