高性能宽带中频信号处理方法研究

高速模数转换器的采样速度达到了GSPS（每秒109次）量级,带宽和量化精度的提升对电路的工作条件提出了更高的要求。分析了高速采样中制约无杂散动态范围的因素,并从实践的角度提出了改善的方案,设计了一套双通道通用中频信号处理硬件平台。测试结果说明系统功能正常。达到了140MHz或70MHz中心频率信号输入时无杂散动态范围80dB的性能指标。     

时间压缩式相关器/延迟线IC设计

相关器、延迟线在信号处理领域中有着非常广泛的应用.但到目前为止尚没有看到这类集成电路 的报道.依据[1]文提及的新型时间压缩式相关器,本文给出了通用相关器/延迟线的专用集成电路设计,该集成电路(IC)可以完成极性相关和多比特相关、同时还可以作为延迟线应用,可构成768级以下任意长延时,在8kHz采样频率下单片IC最大延时可达96ms.此IC可以多片应用,满足不同场合的应用要求.     

基于小波树和哈达玛矩阵的自适应快速三维压缩成像方法

针对光子计数系统实现三维成像速度缓慢的问题,提出一种基于小波树和哈达玛矩阵的自适应快速三维压缩成像方法。利用哈达玛矩阵调制投影图案提高采样效率,被调制的短脉冲结构光照射场景,单像素光子计数探测器采集回波。通过分析低分辨率图像的小波树选择采样区域,使用哈达玛矩阵调制所选采样区域得到的投影图案,可采集图像细节,多阶段采样后利用哈达玛反变换恢复出高分辨率图像。实验结果表明,采集并恢复出一幅512×512像素的三维图像的时间最快可达到41 s。     

基于PCIe总线的数据采集卡设计与实现

为了实现对多路高速光信号采集,利用FPGA设计基于PCIe总线的数据采集系统。对PCIe总线低速Slave通道与高速DMA通道的关键算法进行了研究。首先,介绍了数据采集卡的硬件构成及基本工作原理,提出了PCIe总线算法需要解决的数据传输问题;然后,分析数据采集卡PCIe总线低速Slave通道和高速DMA通道原理以及实现的关键算法。通过Modelsim和SignalTap工具分别对数据传输算法进行功能验证和在线仿真;最后,将设计数据采集卡互联PCIe上位机进行实际测试。实验结果表明,本设计PCIe总线采用X4接口模式,数据传输系统的数据上传峰值速率为615.38MB/s,可以满足稳定可靠、高带宽、模块化等要求。     

基于二维光子晶体点缺陷可调谐光功率分配器

在二维矩形阵列结构硅光子晶体中去除中间一排硅柱形成线波导,在线波导右侧引入点缺陷。利用时域有限差分法(FDTD)模拟仿真以及数值分析研究线波导中光耦合特性,计算出两个通道的分光比,发现改变光子晶体的温度可以明显改变这两个通道的光功率比。基于此结构,提出了一种新的光功率分配器,可以获得大范围的光功率比值,从1∶1～90∶1都可以通过改变光子晶体的温度来实现,并且当温度从0℃～200℃就可以实现这一功能,最后设计了一款三通道可调谐光功率分配器,通过调节两个点缺陷区域内温度来实现光功率的分配。     

一维光子晶体的双通道位置设计及调整

通过对法布里-珀罗滤光片性质的研究,以及对法布里-珀罗滤光片中缺陷层厚度变化对通道数目、位置影响的分析,为双通道一维光子晶体的设计提出了一条新的思路。在法布里-珀罗结构的基础上引入一维光子晶体的双对称结构,并通过改变双对称结构的三个缺陷层厚度来实现对禁带内两个通道系列位置的独立调整。设计过程中采用有效界面法对通道的位置进行初步的计算,并通过计算机理论模拟对膜层进行修正,使通道的位置满足设计要求。设计结果表明,通过调整两个厚度参量可以克服双通道一维光子晶体中的通道干涉现象,从而实现通道位置的独立调整。     

基于时间相关单光子计数的荧光寿命成像技术

采用时域法中的时间相关单光子计数方法记录荧光寿命,时间相关单光子计数采用多波长通道同时记录荧光光子数,可以提高计数效率和信息量,还可以在稳态图像中分离不同荧光团,形成4维图像。并采用多光子激发技术,利用长波长光源发出的两个或多个光子可以激发出一个短波长的光子。多个光子必须几乎同时到达激发点,才能提供被激发分子足够的能量以产生荧光。多光子激发波长较长,生物组织对其散射减小,因而可以穿透到更深层的组织,从而提高荧光成像深度和空间分辨力,并减少对活体样品的损伤。     

一种基于地址-事件表达的实时视觉传感器实现方法

为获取高帧频、大动态范围、低数据量的精确视觉信息,提出了一种基于地址-事件表达(AER)的实时视觉CMOS传感器实现方法。采用AER方式,多模式的行仲裁及实时时间标记,有效减小读出数据量,减小时域行间信息扭曲;利用像素级光强变化感知电路探测光强变化,双采样脉冲宽度调制(PWM)电路量化光强。仿真结果显示,在100lx光强下,获得最小等效帧频1000frame/s,10lx光强下为100frame/s,静态动态范围大于133dB,视频动态范围48.16dB,并可实现实时时间标记、多模式仲裁的功能,减小输出数据量11.61%～42.74%。结果表明,该方法可完成实时视觉信息的采集、处理、输出,适用于高速、高动态范围视觉领域。     

实时通用时间压缩式相关器

六十年代以来,时间压缩式相关器在主动声呐的匹配滤波中得到广泛应用,但是由于受数据长度、采样频率等的限制,这种模型不能直接用于被动声呐。否则会引起数据的丢失。本文提出一种交叉存取式时间压缩相关器,利用一个缓冲存贮器可以实时完成任意长数据的相关运算,从而解决了主、被动声呐中所需的相关器设计问题。文中给出了正序、逆序进动型数据链及移位型正序、逆序数据链的流程图和硬件实现的方框图。本文讨论的方法可用于数字式声呐的设计,大大简化系统和提高声呐性能。     

基于光子晶体带隙特性的反射式多通道滤光片设计

反射式多通道滤光片在光学通讯、光学成像、遥感高光谱等方面有着重要的应用。利用含缺陷一维光子晶体独特的带隙特性,依据其相应的能带理论,设计了一种由金属和介质组成的反射式多通道滤光片。这种滤光片通道的工作范围由光子带隙理论计算得到,通道个数由"光子晶体"缺陷的周期数决定,通道的位置利用等效相位厚度的方法确立。相对于传统的以经验为主的反射式多通道滤光片设计方法,这种基于光子晶体的带隙理论的设计能够从"光子"的角度给出此类反射式滤光元件的设计思路和理论解释。     

Phase filters for correlators with incoherent light

Optimized phase filters can be designed and incorporated into hybrid electronic-optic correlators that exploit incoherent light. These filters lead to high optical efficiency and little, if any, loss of information that normally result from discarding amplitude data. The optimization procedure was experimentally tested by recording optimized filters in photo resist and incorporating them into the correlator. The optimization algorithm, the filter recording procedures, and the experiment correlation results demonstrating the efficacy of our design are presented. These results are superior when compared to those of correlators using holographic filters.     

Increase of reliability of surface displacement field recovery by optical speckle-displacement correlation technique

The optical speckle-displacement correlation (OSDC) technique was developed to increase the reliability of surface displacement field recovery near stress concentrators. The performance of optical speckle correlators based on joint transform correlator (JTC) architecture and a joint power spectrum (JPS) nonlinear filtering (median thresholding, adaptive median thresholding, ring median thresholding) is studied by using computer models of these correlators. The design of hybrid joint transform speckle correlator is detailed. Example results of correlation signal using computer models of digital speckle correlation and OSDC techniques and created hybrid joint transform speckle correlator setup are described.     

Dimensionally reduced U(1)+Higgs theory in the broken phase

We apply dimensional reduction to the finite temperature U(1)+Higgs theory and study the properties of the reduced 3-dimensional theory in the broken phase using lattice Monte Carlo simulations. We compute analytically the scalar condensate in optimized 2-loop perturbation theory and the correlators in 1-loop perturbation theory. These quantities are also calculated numerically. The two results for the condensate agree well but a 25% difference is observed for the scalar correlator, indicating the need for optimized 2-loop perturbative results.     

Dynamic theory of two-photon correlators in the spectroscopy of single impurity centers

A dynamic theory of two-photon correlators measured in experiments with single molecular impurity centers has been developed. The theory takes into account the interaction between optically active electrons of an impurity center and phonons, excitations in tunneling systems of polymers and glasses, and transverse electromagnetic field. Both the correlator measured in the start-stop regime and the “full” correlator have been analyzed, and equations for these correlators have been derived. An equation relating these two correlators has been also obtained. The effect of the triplet level of an impurity molecule on the correlators leading to bunching of spontaneously emitted photons has been studied. The two-photon correlators have been calculated numerically, and their dependence on the incident light frequency and time between the pairs of detected photons in various realistic situations has been derived. Zh. éksp. Teor. Fiz. 113, 1606–1631 (May 1998)     

Optical correlation techniques in fluid dynamics

Three flow measurement techniques make use of fast digital correlators. The most widely spread is photon correlation velocimetry using crossed laser beams, and detecting Doppler shifted light scattered by small particles in the flow. Depending on the processing of the photon correlation output, this technique yields mean velocity, turbulence level, and even the detailed probability distribution of one velocity component. An improved data processing scheme is demonstrated on laminar vortex flow in a curved channel. In the second method, rate correlation based upon threshold crossings of a high pass filtered laser Doppler signal can be used to obtain velocity correlation functions. The most powerful set-up developed in our laboratory uses a phase locked loop type tracker and a multibit correlator to analyze time-dependent Taylor vortex flow. With two optical systems and trackers, cross-correlation functions reveal phase relations between different vortices. The last method makes use of refractive index fluctuations (eg in two phase flows) instead of scattering particles. Interferometry with bidirectional counting, and digital correlation and probability analysis, constitutes a new quantitative technique related to classical Schlieren methods. Measurements on a mixing flow of heated and cold air contribute new ideas to the theory of turbulent random phase screens.     

Multitarget Detection Using a Fringe adjusted and Power Spectrum Subtracted Hybrid Optical Joint Transform Correlator

１ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｏｐｔｉｃａｌｐａｔｅｒｎｒｅｃｏｇｎｉｔｉｏｎ,ｔｈｅｊｏｉｎｔｔｒａｎｓｆｏｒｍｃｏｒｅｌａｔｏｒ［１］（ＪＴＣ）ｉｓｍｏｒｅｓｕｉｔａｂｌｅｆｏｒｒｅａｌｔｉｍｅｏｐｔｉｃａｌｐａｔｅｒｎｒｅｃｏｇｎｉｔｉｏｎａ...     

激光诱导液晶定向研究

Multiple target detection using a fringe-adjusted and power spectrum subtracted joint transform correlator is proposed. The best factor of the filter to deliver the best correlation output performance is found through computer simulation tests and the result is verified by a programmable single spatial light modulator joint transform correlator. The technique is found to deliver a better correlation output and the capacity to accommodate noise in the input scene than the classical, the previous fringe adjusted and modified fringe adjusted joint transform correlators.     

基于绝对差度量的灰阶图像光学匹配运算

讨论了基于绝对差度量的灰阶图像识别问题;利用光学相关原理和循环编码方法实现了基于绝对差度量的灰阶图像快速匹配处理;基于差异度矩阵和λ截集的概念来描述匹配结果,提高了灰阶目标识别抵抗各种畸变干扰的稳定性。此方法可以适用于任何的相干光和非相干光相关系统,给出了实验示例。     

Anomalous scattered light correlator

The space-time correlation function of the scattered radiation intensity of atoms situated in an external field is investigated. This function includes contributions of the normal +E^–> and anomalous –E–> complex field amplitude correlator. These correlators have components due to scattering by density fluctuations and to collective, diffraction effects. The spatial structure of these correlators is studied and the conditions for the measurement of the anomalous correlator are derived. The temporal properties of the anomalous correlator and the effect of Doppler broadening on the correlation properties of scattered radiation are also considered. The investigation of the anomalous correlator is of interest in high-resolution spectroscopy and may also be useful in the study of nonresonant media.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 70–73, February, 1982.     

Apochromatic optical correlation

Optical correlation, or matched filtering, can now be applied more widely than before, because the light is now allowed to be totally incoherent, spatially and spectrally. Two such correlators were demonstrated recently. Their state of chromatic correction can be called achromatic, since the scaling error has two zero crossings within the visible range of wavelengths. We present a new apochromatic correlator, in which the scaling error has three zero crossings. The maximum error and the rms error are reduced by a factor of 5. Our apochromatic correlator is composed of two highly dispersive heavy flint lenses that are in contact with two diffractive lenses and two chromatic corrected refractive lenses. The uncommon combination of flint dispersion and diffractive dispersion enabled us to achieve apochromatic correction of the scaling factor of the correlator.