Speckle reduction in holography by means of random spatial sampling

In this paper, we will illustrate a new technique by which the hologram image speckle can be reduced by spatially random sampling of the hologram aperture. The sampling procedure can be performed by a movable random mask. If the sampling function is made to be uncorrelated in subsequent spatial sampling, the speckle effect in the hologram image can be eliminated. However, an optimum sampling function may be difficult to obtain, which remains to be seen. This speckle reduction technique can be achieved only by some trade-off of the holographic resolution. A simple experimental confirmation of this technique is illustrated. Since one of the most severely limiting factors in applications of holography may be the speckle effect, this proposed technique should be added, together with the other existent techniques, to remedy this limiting factor.