Comparative Studies for Reconstruction Algorithms of Object Wave Front in Microscopic Digital Holography

Based on the theorems of holography and linear system,the numerical reconstructing methods of the off-axis lensless Fourier transform hologram by Fresnel diffraction formula and by the convolution method based on Rayleigh-Sommerfeld diffraction integral and by angular spectrum theorem are studied.Both results of the theoretical analysis and the computer simulation show that the quality of the images acquired by Fresnel approximation and by angular spectrum method are better than by convolution,and the reconstructing rate by Fresnel method is fastest.Although the Fresnel approximate condition isn′t fulfilled in the condition of very short recording distance,Fresnel diffraction formula is still correct.The characters of the fast Fourier transform of the free space impulse response are related to reconstructing distance,so the quality of the reconstructed image by convolution is idea only in a special condition. For the minimal object field and large-aperture hologram,Fresnel approximation method is ideal.