Depths of view and focus of digital holographic imaging system

Abstract

There exist some ambiguities about the depth of view (DOV) and depth of focus (DOF) of digital holographic imaging system (DHIS). Based on the principle of digital holography, the DOV and the DOF of the DHIS is analyzed in detail for the first time to the best of our knowledge. For the four common configurations for recording digital holograms, the axial complex amplitude and the intensity distributions of the reconstructed optical field of a point object are deduced respectively using Fresnel diffraction formula. According to the same criterion in common coherent imaging system of the lens (CCISL), the DOF of the DHIS is obtained. The results show that the DOV and the DOF of the DHIS are related not only to the optical wavelength and the numerical aperture of the CCD camera but also to the offset of the reference light wave. The DOF of the CCISL is found larger than that of the digital in-line holographic system. But the DOF of the digital off-axis lensless Fourier transform holographic imaging system, which is depended strongly on the offset of the reference point source, may be larger or smaller than that of the CCISL. The computer simulation results confirm the validity of the theoretical analysis.