Method for suppressing speckle noises of computer-generated holography

Abstract

The invention puts forward a method for suppressing speckle noises of computer-generated holography. According to the method, diffraction optical elements having random phase distribution and sub holograms are generated respectively and the diffraction optical elements and the sub holograms are loaded to two SLMs for representation. With the diffraction optical elements, the represented light coherence can be reduced; the sub holograms enables adjacent pixel points to be separated in space; and with time multiplexing, suppression of represented speckle noises is realized.

Description

technical field [0001] The present invention relates to the field of holographic display, in particular to a method for suppressing calculation holographic speckle noise. Background technique [0002] Speckle noise is one of the reasons for reducing the quality of computed holographic reconstructed images. In order to improve the quality of reconstructed images, a variety of methods for suppressing speckle noise have been proposed. Among them, the representative methods are: iterative method, weakly coherent light reconstruction method, Temporal averaging and pixel separation. The Gerchberg-Saxton algorithm is the most common iterative algorithm. This method suppresses the speckle noise by increasing the number of iterations of the algorithm, but with the increase of the number of iterations, the convergence of the algorithm becomes worse, and the effect of noise suppression is not obvious. The weak coherent light reproduction method uses a light source with poor coherence ...

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Problems solved by technology

The Gerchberg-Saxton algorithm is the most common iterative algorithm. This method suppresses speckle noise by increasing the number of iterations of the algorithm, but with the increase of the number of iterations, the convergence of the algorithm becomes worse, and the effect of noise suppression is not obvious.

The weak coherent light reproduction method uses a light source with poor coherence (such as LED) as the reproduced light. This method can effectively suppress speckle noise, but it will blur the reproduced image.

The time averaging method is also called the random averaging method. In this type of method, multiple holograms need to be produced for each recorded scene, and then the speckle noise is suppressed by time averaging. This type of method increases the calculation burden of the hologram and has a negative The refresh rate of the spatial light modulator (SLM) puts forward higher requirements, and it is difficult to realize dynamic display

The pixel separation method divides the recorded object into multiple object point groups, and suppresses speckle noise by reducing the overlapping area of ​​adjacent Airy disks. This method still needs to record dozens of holograms for each recorded scene, which is not conducive to the realization of dynamic holography. show

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