The optical components employed in high power density solid-state laser for inertial confinement fusion (ICF) must be measured at full aperture to provide the higher resolution measurements necessary to detect mid-spatial-frequency errors in the wavefront. The use of Fourier analysis techniques to measure the wavefront power spectral density (PSD) in mid-frequency domain is discussed. A large phase-shifting Fizeau interferometer is used for the measurement. The phase wavefront detected by the interferometer is digitally processed to create one dimension wavefront PSD. The PSD of several optical components are shown.