光学相关识别2f+p系统

Optical Correlation Recognition 2f+p System

VanderLugt光学相关器中含有两个傅立叶变换透镜 ,从输入面到输出面的光学长度是 4f,在制作复数滤波器时 ,参考光是一束倾斜入射的平行光。我们设计的复数滤波器带二次位相因子的光学相关识别 2f+p系统 ,在制作复数滤波器时 ,参考光是一束倾斜入射的会聚光 ,使复数滤波器包含一个二次位相因子 ;在进行目标识别时 ,只需一个傅立叶变换透镜 ,复数滤波器后面不再使用傅立叶透镜进行傅立叶逆变换 ,而是直接通过复数滤波器的衍射 ,在其后的p平面上得到分离的相关峰 ,因此从输入面到输出面的光学长度是 2f+p ,与VLC相比 ,不光减少一个傅立叶透镜 ,光路也较VLC短许多 (通常p比f小许多 ) ,使光学相关识别系统结构更为紧凑。坦克模型识别实验证明 ,2f+p系统用于光学相关识别 ,相关峰强而尖锐 ,且与零频项和卷积项能很好的分离 ,信噪比很高。多个星形合作目标识别实验 ,证明 2f+p系统与VLC一样具有平移不变性 ,而星形合作目标本身具有一定的旋转、比例不变性 ,因此可用于导航、盲降等多种用途。实验取得良好的效果。并且给出了详细的理论推导。

Vander Lugt correlator needs two Fourier transform lenses.The distance from input plane to output plane is 4f.The reference light is slant and parallel when the complex filter is being built for VLC.We design a optical recognition 2f+p system whose complex filter contains quadratic phase term.Different from VLC the reference light is slant and concentrated when the complex filter is being built for our 2f+p system,which means its complex filter contains a quadratic phase term.When the 2f+p system is recognizing the object,the output correlate peak can be observed directly after the complex filter other than after a Fourier lens in VLC because of diffraction.So that the 2f+p system needs only one Fourier lens,and is much shorter and more compact than VLC.The experiment of the 2f+p system recognizing tank model shows that the correlate peak is bright and sharp,the SNR is large.The correlate peak separates well from the zero frequency term and the roll term.The experiment of the 2f+p system recognizing the cooperate star-shape targets shows that it also has the character of shift invariability as VLC.The cooperate star-shape target itself has the characters of rotate and ratio invariability.So the 2f+p system with the cooperate star-shape targets can be used for navigation and auto landing,etc.The experiment work out good results.Its theory is deduced detailedly.