In this research we presented a novel method based on frequency domain interferometry to in situ measure the cupping deformation of diamond anvils under high pressures.First we introduced the working principle of the cupping deformation measurements based on the frequency domain interferometry,and then we carried out the experiments under high pressures.The cupping deformation of diamond anvils is obtained under high pressures up to 42.1 GPa,and its maximum value reaches 11.1μm.The experimental results show...