Assessing digital micromirror devices for speckle noise control in digital holography

Abstract

Speckle noise is a common issue in coherent imaging techniques. As one of these techniques, digital holography (DH) is affected by this problem. Although several attempts have been made to overcome speckle noise in the numerical reconstruction of digitally recorded holograms, there still exists the need for fast and effective methods to get rid of speckle and improve image quality. We assess the suitability of a digital micromirror device (DMD) as modulator of the object illumination in a digital holographic setup, where the DMD acts generating speckle-like patterns that are projected onto the object. These patterns change the object beam in a random way. Several holograms, each with a different pattern in the object illumination, are recorded and numerically reconstructed. The image with reduced speckle noise is the result of a superposition in an intensity basis of various such reconstructions. The feasibility of the method is validated by experimental results.