The laser-based transmitter used in this Letter is composed of an integrated optical Mach-Zehnder interferometer, which was first used in fault diagnosis. With the help of the effective signal processing method and laser-based integrated optical Mach-Zehnder (IOMZ) system, the location of the defect in an aluminum plate can be successfully determined. Moreover, a comparison study is conducted to investigate the effectiveness of both the conventional laser spot source and the IOMZ interferometer-based laser source. The results indicate that the IOMZ interferometer-based method can be very useful to the nondestructive testing research field. The potential for industrial applications is also significant, especially for the health monitoring and integrity inspection of metal plates.