Speckle reduced holographic displays using tomographic synthesis.

Despite significant merit of depth representation, holographic displays have a considerable limitation: speckle. Here, we present speckle reduced holographic displays using an engineered light source with angle diversity for speckle reduction. The level of angle diversity is optimized with consideration of resolution, speckle contrast, and depth of field. To extend the depth of field sacrificed for speckle reduction, we apply tomographic synthesis, exploiting synchronization of a local illumination module and a tunable-focus lens. We implement a benchtop prototype to verify the proposed method, which reduces the speckle contrast averagely by 37.8% while preserving resolution and 4.0 diopter depth of field.