Digital synthesis of multiple off-axis holograms with overlapping Fourier spectra

By applying tilted illumination on an object we record different sections of its Fourier spectrum in a row. We make use of an overlap between these sections to calculate their spatial frequency shift in sub-pixel accuracy by correlation methods. The global phase difference between the sections is corrected by subtracting the phase values of the overlapping areas and plotting them into a histogram. In this way the phase difference is measured with an accuracy of ± 0.10π. Also the amplitude adjustment between different spectral sections is demonstrated. An experimental setup for synthetic aperture digital holography using tilted illumination is presented and a detailed description of the digital aperture synthesis is given. The method is applied to improve the resolution of a holographically recorded object.