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1 Introduction Pupil planefilterscanbeusedtochangethelightintensitydistributioninthefocalplane ,sotheyhavepotentialapplicationsintheareasofopticaldatastorage[1~ 3 ] ,lithography[4] ,andmicroscopy[5~ 7] .Manypupilfiltershavebeenstudied ,suchasfilterswithvariedamp… 相似文献
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基于级联分数傅里叶变换系统的数字水印技术 总被引:1,自引:0,他引:1
提出一种基于分数傅里叶变换和随机相位编码的光学加密数字水印技术,可成为一种信息隐藏及保护的有效方案.该数字水印技术对于噪音叠加和常见的图像处理操作具有较强的稳健性.该技术根据光学级联分数傅里叶变换系统,利用两个随机相位分布函数对水印信息编码并经过迭代分数傅里叶变换嵌入到变换域的载体图像中.在水印检测和提取过程中,两个相位分布函数作为密钥.随机相位编码技术的引入,进一步提高了数字水印系统的密钥空间.增强了系统的安全性.该数字水印技术基于光学分数傅里叶变换原理,可以利用光学变换系统方便地实现. 相似文献
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Rectangular annular pupils are designed. The transverse intensity distribution and the superresolving characteristics of the pupils in the focal plane are analyzed. The influences of total annular zone numbers and the central core magnitude on the light efficiency (the Strehl ratio S), the superresolving power (the normalized spot size G) and the intensity of sidelobe are studied in detail. The properties are different for two kinds of pupils: one with total odd annular zone numbers and another with total even annular zone numbers. Circular annular pupils are also discussed and the comparison between them is given. 相似文献
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