The recording of digital hologram at short distance and reconstruction using convolution approach

By adopting in-line lensless Fourier setup and phase-shiftingtechnique, we recorded the phase-shifting digital hologram at shortdistance. As the Fresnel diffraction condition is no longer valid,the convolution approach is chosen for the reconstruction. However,the simulated reference wave for the reconstruction would sufferfrom severe under-sampling due to the comparatively large pixelsize. To solve this problem, sinc-interpolation is introduced to getthe pixel-size of the hologram reduced prior to the reconstruction.The experimental results show that an object image of high fidelityis obtained with this method.