提出一种激光超声波成像技术对奥氏体不锈钢焊缝中的人工缺陷进行检测，利用NdYAG脉冲激光器对奥氏体不锈钢焊缝进行扫查，对接收到的超声波信号进行离散正弦/余弦变换(DST/DCT)和希尔伯特变换（HT）。常规的超声波成像方法不能有效检测焊缝边界及焊缝中的人工缺陷，采取离散正弦/余弦变换和希尔伯特变换相结合的激光超声波成像技术不仅能直观、高效地检测出焊缝边界，而且对焊缝中的缺陷位置、大小及形状等也能有效检测。离散正弦/余弦变换和希尔伯特变换的激光超声波成像技术为焊缝缺陷中的定量检测提供了基础。

A technique of laser ultrasonic imaging is proposed to detect austenitic stainless steel weld with artificical defects. Austenitic stainless steel weld is scanned using the pulse of NdYAG laser, and the received ultrasonic wave is transformed by discrete sine/cosine transform (DST/DCT) and Hilbert transform (HT). The conventional ultrasound imaging method can not effectively detect the weld edge and the artificical defect, however, laser ultrasound imaging technology, which combines DST/DCT and HT, can not only directly and efficiently detect the weld edge, but can also detect the location, the shape and the size of damage in the weld. Therefore, the laser ultrasound imaging technology based on the discrete sine/cosine transform and Hilbert transform provides the basis for quantiative detection.