In order to realize three dimensional structure measurement by digital holography

the aberration and its reduction of the phase reconstructed based on Fresnel approximation algorithm are discussed. First

total aberrations of phase reconstructed based on Fresnel approximation algorithm are analyzed

then the digital recording and numerical reconstruction of hologram of phase grating are simulated by computer. Further

the influence from the defocus

the aberration of digital reconstruction light and the depth of the tested samples on the phase reconstructed is simulated and analyzed. It presents the phase subtraction of hologram method to eliminate the phase aberration from the recording light wave and optical parts. Because this aberration has ambiquity characteristic

the experimental results are provided to validate this method. Simulation results indicate that the error from Fresnel approximation arithmetic

the defocus aberration

the digital reconstruction light wave and the wrong unwrapped processing will effect the phase to be reconstructed rightly. High precision phase reconstructed can be gotten when the recording process

reconstruction parameters and the reconstruction method are controlled strictly and selected properly.