Full image reconstruction with reduced speckle noise, from a partially illuminated Fresnel hologram, using a structured random phase.

In computer generated holograms, a random phase is added to spread out the object wave, but this introduces a strong speckle noise in the reconstructed image. Spreading out the object wave helps to record a large object in a smaller hologram. We propose a random repeated and displaced phase, which reduces the speckle noise in the reconstructed image and spreads out the object information in a limited area. The phase is independent of the object, and it could be calculated by sections reducing the hologram computing time. We present simulated and experimental results that prove the improvement in quality of the reconstructed image and the whole object reconstruction, using only a small part of the hologram.