平面反射镜组在光学相关器中的应用

为了解决光学相关器无法与发生旋转的目标进行光学相关识别的问题,提出了使用平面反射镜组获取目标图像,与模板图像进行相关识别。在获取目标的光学系统中,加入一个由多个平面反射镜围成的正多棱柱体,它可以使目标产生的一组不同角度的镜像,将其作为目标图像与模板图像进行相关识别。可以从不同旋转角度的目标产生的镜像组中找到角度相似的镜像,这类目标图像与模板图像进行相关运算,能够得到相关峰。实验表明,将通过平面反射镜组获得的目标的镜像组作为目标图像,是解决光学相关器针对旋转目标识别问题的有效途径。     

基于多变量鉴别分析的光学畸变不变性图像识别

提出一种基于鉴别分析的光学畸变不变性图像识别方法：对包含各种畸变的训练图像集采用主成分分析得到若干本征图像,作为参考模式与测试图像做光学相关,利用本民输入图像的相关结果作为识别特征,采用最佳鉴别分析做了训练和识别,即可实现对输入图像的畸变为性快速识别。采用非相干光相关器为光学实现硬件,给出了实验结果。     

一种提高光学相关模式识别准确性的后处理方法

将基于绝对差算法的最小距离离度量方法用于光学相关器产生的相关结果灰度图像的相假性度量,并以此为依据给出待识别图像与参考图像之间的相似性结论,避免了传统的以相关联峰取阈为判决依据引起误判现象,提高了判决准确率,甚至可以对由灰度图像直接做光学相关得到的低质量相关结果给出准确判断,从而避免了对灰度图像做二值化及编码处理等烦琐的预处理工作,采用非相干相关器为光学实现硬件并给出了实验结果。     

光学相关器在自动目标识别中的应用

为使光学相关器更好地应用于自动目标识别领域,保证在较高识别速度下,具备良好的识别效果,介绍了应用于自动目标识别领域的联合变换相关器和匹配滤波相关器.针对匹配滤波相关器实现过程中的两项关键技术,在滤波器编码技术上提出了构造等相关峰综合鉴别函数以解决畸变不变识别问题.在相关峰识别技术上,针对阈值法存在的不足,提出利用BP神经网络对相关平面相关峰进行识别,采用划分感兴趣区域的方法减少了输入层神经元数目,简化了神经网络结构.借助搭建的光学相关器系统验证了该方法可对相关信号和噪声进行有效分类,提高了光学相关器的识别效果.     

联合击中击不中变换相关器

将联合击中击 中变换相关器用于二值图像的目标识别。与常用的联合变换相关器相比，联合击中击不中变换相关器对联合变换相关器输入图像和参考图像进行互补编码。编码的目的在于通过联合变换相关器来一步实现形态学中的击中击不中变换。     

BP神经网络在光学相关器相关峰识别中的应用

光学相关识别是图像识别的重要方法，有效识别相关器输出平面的相关峰信号是保证光学相关器图像识别准确性的关键。由于激光器输出功率的波动、光学系统本身的误差以及SLM器件本身带来的噪声，采用一般的阈值方法很难达到理想的效果。该文提出对相关器的输出平面进行预处理，充分考虑相关信号的形状信息，提取感兴趣区域(ROI)，采用BP神经网络对输入矢量进行计算，可达到对相关峰信号和噪声的有效分类识别，从而提高了光学相关器识别的可靠性，降低了误判的概率。     

新型平面集成光学相关器设计与分析

基于微光学与二元光学技术,设计了一种新型的平面折叠式光学相关器,将相关器中组成4f系统的傅里叶变换透镜、全息匹配滤波器、输入面和输出集成到一个平面器件上,与另一平面偏振反射镜构成一个反射型的平面光学系统.讨论了相关器的系统结构设计、系统参数的设计,给出了具体的设计模型,计算出其体积可减小至约12 cm3.利用菲涅耳衍射数值模拟方法对系统的图像识别过程进行了仿真,得到了良好的相关输出结果,证实平面集成光学相关器具有很好的识别性能.     

基于超混沌和Gyrator域相位信息复用的光学多图像认证方法

针对光学多图像认证方法中,多路复用图像中的串扰噪声,以及不同认证级别下的信息安全问题,提出了一种基于超混沌振幅型掩模和Gyrator变换域下相位信息复用的光学多图像认证方法。利用分数阶超混沌Rabinovich系统构造超混沌随机振幅掩模;基于改进的Gerchberg-Saxton算法对原始图像进行低级或高级编码,利用超混沌掩模作为振幅约束,迭代获得目标图像,并将得到的N个目标图像编码成复合图像;再次通过Gerchberg-Saxton迭代将复合图像转化为两个便于传输的纯相位掩模。实验结果表明:在认证过程中,不同安全级别的用户拥有各自的认证密钥,低级认证过程中可以通过检索图像与原始图像的非线性相关峰值,判断认证图像的正确性,而高级认证过程中则可以获得与原始图像相似度较高的认证图像,峰值信噪比和相关系数分别可达25.2817 dB和0.9844。所提方法对遮挡攻击和噪声攻击具有良好的稳健性,为多幅图像在不同级别下的光学认证提供了新的思路。     

一种新的相位编码幅值调节联合变换相关器

给出了一种对经典联合变换相关器进行相位编码和幅值调节的新方法,使联合变换相关器具有优化的相关输出信号和很强的抗干扰能力.在相位编码幅值调节联合变换相关器中,输入的待识别信号首先通过相位模板进行相位编码,然后对联合功率谱进行幅值调节滤波.在进行幅值调节滤波时采用了增强型幅值调节滤波器,其调节因子可根据输信号的噪音干扰情况进行调节变化.相位编码幅值调节有效地祛除了多目标识别联合变换相关器的冗余信号,可广泛的应用于多目标识别.     

基于功率谱压缩-平移的多通道联合变换相关识别方法研究

为了充分利用光学相关识别系统的空间-频谱带宽,提高光学相关识别技术的并行处理效率和识别准确度,提出了基于功率谱压缩-平移算法的多通道联合变换相关识别方法,该方法将峰值位置变化的标准差作为相关识别的判据.在输入空间光调制器的不同区域加载场景图像和N幅参考图像,然后在图像上分别叠加经迭代算法优化的相位模板,使得场景图像的傅里叶谱和每一幅参考图像的傅里叶谱在频谱面的不同空间区域相干叠加.调节相位优化算法的约束参量,使得每个通道的联合变换功率谱互不干扰,可实现N个通道的并行处理.分析了不同优化相位的傅里叶谱的局域峰值杂波均值和相关输出的峰值位置变化标准差之间的关系,并将其作为相位优选的依据.研究结果表明,在所提实验和数值模拟参数条件下,多通道联合变换相关识别系统可以在不增加经典相关识别系统复杂度的前提下,实现16通道的并行处理,这对光学相关器的实用化具有重要意义.     

Printed Chinese character recognition with a real-time optical correlator

A prototype real-time Chinese character recognition processor, which utilizes the Vander Lugt type complex spatial filter is presented. A real-time correlation operation is performed with a photoconductor-liquid crystal device as an incoherent-to-coherent image converter. Bandpass Fourier transform images passing through a bandpass spatial filter are sequentially recorded on a rotating hologram recording plate as stored reference patterns. It makes possible holding the stable discrimination for noisy unknown input patterns and storing a huge number of reference patterns. The typewritten Chinese characters in practice are experimentally discriminated from very similar ones in the real-time optical correlator. This indicates the possibility of more than 2000 printed Chinese character recognition with the optical correlation.     

Imaging through a scattering medium with an interferential spectrometer by selection of an amplitude modulation correlator

Low-coherence interferometric systems provide three-dimensional imaging through scattering media by measurement of the object's temporal response. An optical correlator is presented that allows direct recording of the signal issued from the object under reflection. The filtering technique enhances the image visibility and allows one to obtain an image with a good signal-to-noise ratio. The performance of two particular imaging systems, point-to-point and vertical-slice imaging, is discussed with an object comprising two cover plates that are attached.     

基于液晶光阀非线性变换的实时光学相关识别

提出了一种高鉴别能力的实时光学相关器，它采用液晶光阀作为实时输入器件，并利用其非线性变换特性对图像微分预处理，全息记录材料采用光折变晶体，且使用全取球面波作参考光。所给出的实验结果表明，该光学相关具有鉴别能力高，实时性和灵活性强，以及结构２紧凑的特点。     

Compressive optical image watermarking using joint Fresnel transform correlator architecture

A new optical image watermarking technique based on compressive sensing using joint Fresnel transform correlator architecture has been presented. A secret scene or image is first embedded into a host image to perform optical image watermarking by use of joint Fresnel transform correlator architecture. Then, the watermarked image is compressed to much smaller signal data using single-pixel compressive holographic imaging in optical domain. At the received terminal, the watermarked image is reconstructed well via compressive sensing theory and a specified holographic reconstruction algorithm. The preliminary numerical simulations show that it is effective and suitable for optical image security transmission in the coming absolutely optical network for the reason of the completely optical implementation and largely decreased holograms data volume.     

The use of a consumer grade photo camera in optical-digital correlator for pattern recognition and input scene restoration

In this work an optical-digital correlator for pattern recognition and input scene restoration is described. Main features of the described correlator are portability and ability of multi-element input scenes processing. The correlator consists of a consumer grade digital photo camera with a diffractive optical element (DOE) inserted as a correlation filter. Correlation of an input scene with a reference image recorded on the DOE are provided optically and registered by the digital photo camera for further processing. Using obtained correlation signals and DOE’s point spread function (PSF), one can restore the image of the input scene from the image of correlation signals by digital deconvolution algorithms.The construction of the correlator based on the consumer grade digital photo camera is presented. The software procedure that is necessary for images linearization of correlation signals is described. Experimental results on optical correlation are compared with numerical simulation. The results of images restoration from conventionally and specially processed correlation signals are reported. Quantitative estimations of accuracy of correlation signals as well as restored images of the input scene are presented.     

Invariant Joint Transform CorrelatorⅠ: Mapping Filter

l.IntroductionAVanderLugtcomp1exlnatchingspatialcorreIator[1jandajointtransformcorrela-tor[z~ejaret``omaJorkindsofcorrelators,however,theyaresensitivetoscalingandro-tationvariance.Thisdisadvantageisaseverelimitationforthemtobeusedinpracticalapplications-Invariantprocessingwiththeclassicalopticalcorre1atorwithproPertiesotherthanPOsitiondemandsthatthepropertyisrepresentedasashift.WithaIog-POlarmafrping[="j,thesizeandorientationw'il1beexpressedasshiftparameters,orratherrotationascyc1icshift.…     

位相调制的实时联合变换相关器

提出一种位相调制的实时联合变换相关器。它采用液晶显示屏作为输入器件，用液晶光阀记录和显示联合功率谱。利用液晶显示屏上的光栅状结构的衍射级，提高光能的利用率，并充分利用液晶光阀的有效使用面积。采用成像透镜放大各衍射级的联合频谱，适应液晶光阀较低的分辨率要求。在相关器的光路中插入两块倾斜的平行平面玻璃板，以改变各衍射级的参考图像和目标图像之间的位相差。这种方法可产生比传统的实时联合变换相关器更好的输出相关性能。实验结果证实了该系统设计及性能分析的正确性     

Optical correlation with totally incoherent light

An optical correlator that can operate with totally incoherent light is presented. Such a correlator can be designed to compensate completely for the inherent chromatic aberrations by resorting to elements with specialized, possibly impractical, dispersion characteristics. Nevertheless, a practical configuration that exploits available achromatic lenses and Fresnel zone plates was designed, built, and tested experimentally. The results reveal that detectable correlation peaks can be obtained with totally incoherent white light. The designs, experimental procedures, and results are presented.