Evaluation of the Thickness of Each Layer of Cu/Al Laminate Using Laser Ultrasonic

A new method of detecting the thickness of each layer of Cu/Al laminates based on laser ultrasound was proposed for the online non-contact measurement of the thickness of each layer of Cu/Al laminates during the rolling process. This method utilized a laser to excite and detect ultrasounds remotely and then obtains the transit time of the longitudinal wave pulse in the copper layer and aluminum layer to calculate their thicknesses. The finite element method was used for investigating the propagation behavior of longitudinal wave in Cu/Al laminate, and the minimum thickness of the copper layer that can be detected by this method was analyzed. The laser ultrasonic experimental platform was set up in the laboratory, and a sample of Cu/Al laminate with step shape was made. The experimental results demonstrate that the laser ultrasound can realize the non-contact and high-precision detection of the thickness of each layer of Cu/Al laminates and has the potential of online thickness measurement.