Resolution analysis of digital holography

The resolutions of the Charge Coupled Device (CCD), the reconstructed image, and the reconstructed image plane in digital holography are theoretically and experimentally analyzed in this paper. Three important conclusions are achieved: (1) By studying the resolution requirements of CCD in different digital holographic recording setups, it shows that lensless Fourier transform holographic recording setup can relax the requirement of the resolution and use the full bandwidth of the CCD sensor, when the object is very small. (2) The resolution of the reconstructed image is mainly determined by the highest spatial frequency of the object wave recorded using CCD, and will increase with the larger CCD size, the higher resolution of the CCD sensor, and the shorter recording distance. (3) The resolutions of the reconstructed image and the reconstructed image plane are different. The latter can influence the quality of the former on display. The resolution of the reconstructed image plane is not only relative to the reconstruction algorithms, but also the parameters of the recording setup. A simple and convenience method is presented, which can effectively increase the resolution of the reconstructed image plane in Fresnel-transform reconstruction of digital holograms. By padding zeros operation to a digital hologram recorded by CCD, the reconstructed image with high quality can be obtained. With similar method, the vision aberration of the reconstructed image due to the difference of CCD size in horizontal and vertical direction can be rectified. Experimental results show a good agreement with theoretical analysis.