散斑调制用于提高体全息相关器的识别率  

Improvement of Correlation Veracity of the Volume Holographic Correlator Based on the Speckle Modulation

作　　者：曹良才[1] 欧阳川[1] 何庆声[1] 廖懿[1] 邬敏贤[1] 金国藩[1] 

机构地区：[1]清华大学精密仪器与机械学系精密测量技术与仪器国家重点实验室,北京100084

出　　处：《中国激光》2005年第2期244-247,共4页Chinese Journal of Lasers

基　　金：国家973计划(G1999033001);国家自然科学基金(60277011)资助项目

摘　　要：　体全息相关器能够进行快速的光学并行相关识别,但是在相关识别的过程中,页间串扰导致相关结果中旁瓣太多,影响了相关峰的判断,大大降低了相关器的识别准确率。为了抑制旁瓣,对传统的体全息相关公式中所产生串扰的因子进行了分析,引入了随机函数的自相关函数作为调制因子对公式进行修正,可以实现在水平方向和竖直方向同时抑制旁瓣,抑制效果与全息图的厚度无关。并提出在相关器的物光光路中物的前方放置随机相位器,实现对物函数的散斑调制。理论分析、数值计算及实验结果表明,该方法可以抑制旁瓣,突出相关峰,提高体全息相关器的识别准确率和通道密度。Volume holographic correlator has advantages for the fast optical parallel recognition. However, because of the inter page crosstalk, the sidelobes occur seriously, which reduces the parallel-processing capacity of the correlator, resulting in the low accuracy of the correlator. To suppress the sidelobes, the traditional correlation formula is analyzed to discuss the origin of sidelobes. It is proposed to modify the formula with the autocorrelation function of a random function, which can suppress the sidelobes in the horizontal direction as well as in the vertical direction, with no dependence on the thickness of the hologram. A diffuser is proposed to be placed in the object path to modulate the object beam with speckle. The theoretical analysis, numerical simulation and experimental results are presented and it is shown that this method can suppress the sidelobes, sharpen the correlation peaks and improve the correlation veracity.

关 键 词：信息光学 全息存储 相关识别 散斑调制 旁瓣抑制 

分 类 号：O438.1[机械工程—光学工程]