In order to investigate the response law of different interferometers to the mid-spatial frequency errors and obtain the relatively true power spectral density(PSD)distribution,the 4D AccuFiz,ZYGO DynaFiz and ZYGO GPI interferometers are respectively used to measure the periodic ripples and scratch samples,and the comparative analysis of the measured one-dimension PSD curves is made.The results show that the responsivities to the mid-and high-spatial frequency information are different for different interfe...