Speckle reduction of kinoform reconstruction utilizing the 2π ambiguity of image phase differences

An iterative speckle reduction method is proposed to reduce the speckle noise in the reconstruction of kinoforms. Because a kinoform only has phase modulation, the phase freedom of the reconstructed image is usually utilized for spectrum smoothing. We consider the speckle noise as isolated zeros among the discrete reconstructed points. An isolated zero leads to a 2 pi circle of the image phase differences. Our proposed iterative speckle reduction method changes the image phase to avoid the 2 pi circles in the reconstructed points. Computer simulations are shown to demonstrate the effect of our method. (c) 2005 The Optical Society of Japan.