Resolution-enhanced digital in-line holography by extension of the computational bandwidth

Higher resolution has always been the goal of imaging. Resolution enhancement in most holographic imaging methods are achieved by collecting more object spectrum. As a computational imaging technology, the resolution of digital holography is determined by the utilized bandwidth in both optical recording and numerical reconstruction. There is little study on whether the collected spectrum is effectively utilized during reconstruction. In this work, we propose a resolution-enhanced digital in-line holography under spherical wave illumination. The collected object spectrum, which cannot be fully used by conventional methods, is effectively utilized by the developed band-extended angular spectrum method with improved computational efficiency. Numerical analysis and optical experiments have been performed to demonstrate that the proposed method can effectively enhance the imaging resolution of digital in-line holography by extension of the computational bandwidth.