Zero order elimination for digital holograms: study of setup dependent methods

In digital holography, reconstructed images are partially obstructed by superimposition of zero order components, due to limited spatial resolution of image sensors. Several techniques have been proposed to minimize or to eliminate this disturbance. Amongst of which, subtraction digital holography consists of subtracting a randomly modified recording from the original one, while HRO or phase shifting methods use controlled images for subtraction. By applying a high-pass filter to the interference pattern, we have proved that zero order elimination in subtraction digital holography cannot be assimilated to a digital filtering process. Theoretical description of the three approaches, as well as corresponding experimental results are presented. To highlight the effectiveness of the methods, we have built a holographic set-up to observe time averaged interferograms of a vibrating membrane. Satisfactory results have been achieved.