光学相关识别2f+p系统

Vander lugt光学相关器中含有两个傅立叶变换透镜，从输入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。我们设计的复烽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VLD相比，不光少一个傅立叶透镜，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 PVLD一样具有平移不变性，百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。     

用计算全息制作自聚焦尺度不变子波变换匹配滤波器

提出了一种基于光学子波变换自聚焦综合判别函数(WFSDF)匹配滤波器。这种匹配滤波器,将光学子波变换和综合判别函数(SDF)相结合,只用一个傅里叶变换透镜就能实现输入图像和SDF的子波变换的相关运算。采用计算全息的方法制作复数匹配滤波器。计算机模拟仿真结果表明,和传统的SDF匹配滤波相关器相比,WFSDF匹配滤波器锐化了相关峰,提高了识别率,同时简化了光路。     

基于改进MACH算法的畸变目标识别

由于观察距离和角度的不同,待识别的目标图像相对模板图像会存在一定程度的角度畸变和比例畸变,大大限制了光学相关模式识别的发展。将最大平均相关高度(MACH)滤波器用于畸变目标识别,通过优化该滤波器的控制参数,并根据多次的计算机仿真实验和光学实验,使该改进型MACH 滤波器具有畸变公差高、相关点明亮等特点。用改进后的MACH 滤波器对角度畸变目标和比例畸变目标实施频域滤波,能有效增强相关峰强度,扩大畸变目标识别范围。作为实例,给出了复杂背景下识别汽车的计算机仿真实验和光学实验,有效验证了该算法的可行性。     

相关场的投影理论及其应用

二维相关方法被用于模式识别、运动、变形、振动等的检测时,对于光学相关方法,精确的光学匹配滤波器必须事先制作出来。由于光学滤波器制作复杂及不易一次制作很多种,从而使其实用性和灵活性受到严重限制。计算机技术的应用,传统的光学相     

计算全息技术在光学相关识别中的应用

为了实现光相关匹配滤波系统的小型化、集成化,采用纯计算全息技术,构建了一个光学相关识别系统.理论分析和实验验证表明,用计算全息透镜代替傅里叶透镜制得的复数滤波器,集成了4f系统中第2个傅里叶变换透镜的作用,滤波器后面不再用傅里叶透镜.这样减少了光学元件,同时缩短了光路.结果表明,该系统和4f光学相关识别系统一样,能够进行相关识别且具有平移不变性.     

用于DWDM的一类光子晶体滤波器

用转移矩阵法模拟计算了通过2组不同禁带的光子晶体级联构成的窄带滤波器的光学特性，设计了信道间隔为0．80nm和0．08nm的密集波分复用（DWDM）光子晶体滤波器。模拟结果表明，这种滤波器的透射特性几乎不受滤波器两边折射率的影响，既可生长在光纤的一端，也可植入光纤内部，还可直接在空气环境中使用，使滤波系统简单、轻便。     

三维空间目标识别的多滤波器技术

本文基于三维空间目标不变性识别的原理,采用多滤波器并行处理和综合判断的光学相关检测技术,对三维空间目标进行识别。实验结果表明仅由４个滤波器构成的滤波器组已能识别出三维目标在水平３６０°、高低角±３０°范围内不同视角的二维平面图像。     

纯相位二值化匹配滤波器的优化设计

通过采用神经网络中的Clipping方法和MonteCarlo修改学习算法,对用于光学模式识别的纯相位二值化匹配滤波器进行了优化设计。计算机模拟结果表明,和传统的纯相位匹配滤波器的相关输出结果相比,其识别输出的信噪比和信号相关峰值得到了明显的提高,从而为今后的光学实现奠定了良好的基础。     

用圆谐综合滤波器实现三重不变光学图像识别

本文在圆谐滤波器算法基础上,结合综合判别函数提出圆谐综合滤波器,解决传统匹配空间滤波器对输入目标的几何形变问题。对合成的滤波器进行了计算机模拟和光学相关实验,结果表明圆谐综合滤波器具有较强的三重不变光学图像识别能力。     

超窄带光学滤波器

叙述了超窄带光学滤波器的基本原理,总结了目前超窄带光学滤波器的发展现状,指出这两种光学滤波器的不足,并提出今后的发展前景。     

基于双正交小波的光阑小波滤波器

提出了一种应用于4f光学系统的光学小波滤波器的设计与制作方法.结合光学信号的优势与小波变换的优点,利用双正交小波的共轭镜像特性构造出了频域形式的分解和重构滤波器.通过将滤波器放置在4f系统的频谱面上对图像成功实现了二维分解和重构.另外还根据信息处理要求和采样器件的特性,制作了振幅型和位相型两种小波滤波器.这两套滤波器都...     

Novel realization of monotonic Butterworth-type lowpass, highpass,and bandpass optical filters using phase-modulated fiber-opticinterferometers and ring resonators

A novel realization of monotonic Butterworth-type lowpass, highpass, and bandpass optical filters (from their electrical digital filter characteristics) by cascading the all-pole and all-zero resonators is presented. A graphical method for fast derivation of the transfer functions, quick inspection of the resonance effects, and important characteristics of any photonic circuits is described. It is shown that incorporation of the optical amplifiers and optical phase modulators into the delay lines of two basic optical resonators, whose pole and zero can be adjusted independently of each other, provides great design flexibility which would otherwise not possible using conventional passive optical resonators. Possible applications of these optical filters as optical pulse equalizers and receiver shaping filters in long-haul coherent lightwave transmission systems are discussed. Possible application of basic resonators comprising of optical phase modulators as tunable optical filters for spectrum analyzers is also considered     

近红外吸收滤光片的制备与性能研究

将两种近红外吸收剂添加到丙烯酸树脂基体中再与PET薄膜复合,制备了可用于夜视兼容照明的双层复合型近红外吸收滤光片.研究了两种近红外吸收剂的吸收特性,以及近红外吸收剂添加量与滤光片吸收性能的关系,并确定了两种近红外吸收剂的用量.所制备的滤光片在660 ～930 nm波长范围内的光线平均透过率为0.10％,能有效吸收发光器...     

可调谐滤波器在DWDM系统中的应用

可调谐滤波器是实现未来全光网络的重要器件,在DWDM系统中有着广泛应用.文章介绍了几种常用的可调谐滤波器的原理、最新研究及其在可重构光分插复用和光传输性能监测中的应用.     

Sensitivity analysis of direct detection optical FDMA networks withOOK modulation

The authors analyze the sensitivity degradation in direct-detection optical FDMA networks as a result of signal filtering (both optical and electrical), interchannel crosstalk, channel beats (or nonlinear crosstalk), and intersymbol interference. The model used is valid for arbitrary linear time-invariant optical filters and received pulse shapes. The analysis is applied to on-off keying (OOK) systems using single-cavity Fabry-Perot filters and multistage Mach-Zehnder filters     

Optical design and performance of wavelength-division-multiplexed optical repeater for fiber-optic passive star networks connection

New optical repeaters that use a wavelength-division-multiplexing (WDM) technique to connect CSMA/CD-based fiber-optic passive star networks are discussed. Two types of optical filters that are essential for obviation of closed-loop formation in construction of such repeaters, have been designed and fabricated. Results of a field trial of the filters and optical modules using the filters show good agreement with design values. The repeaters were also found to operate reliably.     

新型光通信薄膜器件

综述了用于城域网的x-skip-0滤光片、可调谐滤光片已及无源光网络的波分复用器,并给出了8-skip-0滤光片和无源光网络波分复用器的第一块滤光片的设计光谱图。     

Design of Narrowband Optical Filters Using Binary Number Sequence Photonic Crystals

A theory to design narrow band optical filters by using a new photonic crystal structure is presented. This new photonic crystal structure is composed of low index layers and high index layers arranged in mod. 4 up and down binary number sequence. The new structure exhibits narrow transmission peaks in the forbidden frequency gap region with high optical transmission (greater than 99.98%) at C.W.D.M. (Coarse Wavelength Division Multiplexing) center wavelengths. The proposed filters use only 8 layers. These new binary number sequence photonic crystal narrowband optical filters are much smaller in size, lower in cost and easier to fabricate as compared to narrowband photonic crystal optical filters based on defect Fractal Cantor multilayers, suggested recently by a group of researchers.     

Tunable optical filters for dense WDM networks

WDM is currently taking over as the leading technology in point-to-point transmission links. For optical implementation of WDM networks, logical functionalities such as wavelength (channel) selection should be carried out in the wavelength domain; thus, the development of dynamic optical devices is required. One key device is a tunable optical filter. Important features of such a filter include low insertion loss, narrow bandwidth, high sidelobe suppression, large dynamic range, fast tuning speed, a simple control mechanism, small size, and cost effectiveness. Here, an extensive overview of the different technologies used to produce tunable optical filters is presented. Among them, fiber filters such as fiber Bragg gratings and fiber Fabry Perot are the most commercialized, yet inherently limited in their dynamic speeds. For high demanding dynamics, micro-machined and acousto-optic filters can offer a good solution for microsecond tuning speeds. Faster tunable devices, in nanosecond tuning speeds, might emerge out of microresonators, electrooptic filters, and active DBR filters