An experiment on Al-Cu impedance-match targets, carried out at the Shenguang highpower laser facility, is described. The shock adiabat of Cu in the pressure region 0.4- 0.8 TPa, measured experimentally, is close to the extrapolated results of the data at lower pressure obtained with a high-explosive loading facility and also is in agreement with the data at high pressure measured in the underground nuclear test environment.