SOPC技术在低温接收机监控系统中的应用

随着低温接收机技术的发展,对其监控系统提出了更高的要求,体现在:系统的实时性,功能的多变性和复杂性。把SOPC技术应用到低温接收机监控系统上,通过自定义IP实现其硬件定制,并移植通用IP,可以满足其多样化的功能需求。     

CCD在光学镀膜宽带膜厚监控系统中的应用研究

讨论了 CCD的主要特性及对宽带膜厚监控系统的影响 ,介绍了典型的 CCD数据采集系统。建立了一套基于 CCD的宽带膜厚监控系统 ,并对该系统进行了光谱标定及光谱补偿 ,给出了提高信噪比及减小非线性影响的处理方法。     

光栅光阀光学特性分析及其在热敏CTP中的应用

光栅光阀(GLV)是一种衍射MOEMS空间光调制器,利用其对激光束的调制作用,可成功地应用于计算机直接制版(CTP)系统中。提出了简化的光栅光阀光学模型,并根据夫琅和费单缝衍射理论和多光束干涉理论对光栅光阀的光学特性进行了理论分析。介绍了光栅光阀在热敏CTP系统中的应用,分析了光栅光阀光学记录设备的结构和成像原理。得出了基于GLV技术的热敏CTP数字成像过程,为国内印刷企业使用这种热敏成像技术提供了理论依据。     

全数字全息术在图像信息隐藏中的应用

提出了全数字全息术在计算机图像信息隐藏中的应用。待隐藏的秘密信息以及公开的承载信息均为灰度级静止图像。首先对待隐藏的计算机信息图进行全息变换,即通过计算全息图的制作步骤制作出全息图的图像文件,然后再进行Arnold对称性变换。在此基础上,将秘密图像嵌入到承载图像的DCT域的中频系数中。全数字全息术的引入进一步增强了隐藏图像的透明性,通过控制制作全息图时的参数可起到加密的作用,相当于增加了一把秘密钥匙,具有较高的保密性和稳健性。     

SPGD算法在光纤激光相干阵列光束控制中的应用

主动相位控制的光纤激光阵列相干合成在提高输出功率的同时能够保证良好的光束质量,其关键技术在于光纤激光相干阵列的锁相控制。基于随机并行梯度下降(SPGD)算法的锁相控制方案不仅具有控制策略简单、系统结构紧凑的优点,而且通过算法性能评价函数和迭代参数的选取,能够对光纤激光相干阵列进行多种锁相控制,从而得到各种形式的阵列合成光束输出,实现与自适应光子锁相元件整列(APPLE)系统阵列的有效契合。理论研究并实验实现了基于SPGD算法的相位控制方案的同相相干合成锁相控制、合成光束主极大偏转控制和空心光束产生等功能,验证了基于SPGD算法的全电光束控制在各种形态光束控制中的可行性。     

差分光学吸收光谱(DOAS)技术在烟气SO2监测中的应用

本文将差分光学吸收光谱(Differential Optical Absorption Spectroscopy,DOAS)技术中的浓度反演方法运用到烟气SO₂监测中.利用SO₂分子在300nm附近具有强吸收的特性,测量出烟气SO₂的吸收光谱,用DOAS方法反演出SO₂分子的浓度,消除了烟气中烟尘、水汽和其它成分的影响,使在线实时测量成为可能,在实验室内对几种SO₂分子浓度样气进行了测量和浓度反演.     

EMD与神经网络在气液两相流流型识别中的应用

本文提出了EMD与Elman神经网络相结合的气液两相流流型识别的新方法.将压差波动信号经验模态分解(EMD)后的固有模态函数(IMF)进行分析、提取IMF能量作为Elman神经网络的输入特征向量,对水平管内的气液两相流流型进行识别.实验结果表明:该方法优于BP网络且稳定、识别率高,具有可行性.     

数字BPM时钟锁相电路的设计与实现

为实现数字BPM时钟系统的锁相,设计了一种基于锁相环同步原理的低抖动、低相位噪声的时钟同步系统。根据锁相环电路工作原理,对数字BPM时钟同步系统的硬件及固件程序进行了设计,实现了外部输入时钟信号与系统内部产生的主工作时钟信号的锁相,并且时钟信号输出的频率及相位均可调整以满足后端ADC采样的要求。测试结果表明,设计可以完成对一定频率范围内变化的外部输入时钟信号的锁相,输出时钟信号抖动满足束流实验要求,为数字BPM后续算法研究提供了基础。     

光学频率梳非线性传输及其在相位噪声探测中的应用

光纤传递链路中相位噪声探测是基于光纤的精确射频标准传递系统中重要组成部分。为解决光纤链路相位噪声探测中节点反射干扰的问题, 本文基于广义非线性薛定谔方程, 理论上研究了窄带光学频率梳在色散位移光纤中的非线性光学传播特性。在理论分析的基础上, 结合密集波分复用架构, 提出了一种基于锁模光学频率梳进行光纤传递射频信号的相位噪声探测新技术, 克服了节点反射干扰, 给出了初步实验验证。     

Performance analysis of integer linear programming optical monitor placement for crosstalk attack detection in different network topologies

In this paper, an optimum optical power monitor placement is formulated in integer linear programming for crosstalk attack detection by exploiting monitoring information from test connections. The experimental results showed that equipping 6 out of 14, 8 out of 15 and 8 out of 16 nodes with optical power monitoring devices in NSF, MESH and GRID topologies are enough to detect the nodes that are traversed by the crosstalk attack in the networks.     

Investigation of high-speed optical FSK generation scheme based on carrier suppression and phase modulation

We propose and numerically investigate a novel high-speed (40-Gb/s and above) optical frequency shift-keying (FSK) transmitter scheme. By optical carrier-suppressed modulation and differential phase-shift-keying (DPSK) to intensity modulation (IM) conversion, only one light source is needed in the proposed scheme to generate high-speed optical FSK signals. By using a Mach-Zehnder modulator (MZM) as phase modulator and an additional delay interferometer (DI) cascaded after the carrier-suppressed MZM to suppress the remaining carrier, the performance of our scheme can compete with the double-light-source counterparts. The transmission performances of the FSK signal generated with the proposed scheme as well as detuning and bandwidth tolerance of the demodulation filter are also carefully investigated. Simulation results show that the proposed FSK generation scheme is very suitable for the next-generation optical access network and optical label switching network. A potential application of our scheme in high-speed passive optical network is proposed.     

直接检测光OFDM系统中的偏振相关损耗研究

对于高速光传输,直接检测的光正交频分复用系统（direct detection optical orthogonal frequency division multiplexing, DDO-OFDM）中的偏振相关损耗（polarization dependent loss, PDL）与偏振模色散相互作用,对系统传输带来较大影响。对DDO-OFDM系统中PDL与一阶PMD作用机理和数学模型进行了分析,并通过数字仿真加以验证。结果表明:在PDL与PMD联合作用下,对OFDM信号幅度及相位均产生影响,通过发送导频序列可有效实现信号均衡;由于输出偏振态随频率产生旋转,PMD效应一定程度上缓解PDL所致系统损伤,差分群时延为50 ps条件下,以10 Gb/s的速率在单模光纤传输480 km,DDO-OFDM系统Q值提高约0.8 dB。     

FPGA-based amplitude and phase detection in DLLRF

The new generation particle accelerator requires a highly stable radio frequency (RF) system. The stability of the RF system is realized by the Low Level RF (LLRF) subsystem which controls the amplitude and phase of the RF signal. The detection of the RF signal's amplitude and phase is fundamental to LLRF controls. High-speed ADC (Analog to Digital Converter), DAC (Digital to Analog Converter) and FPGA (Field Programmable Gate Array) play very important roles in digital LLRF control systems. This paper describes the implementation of real-time amplitude and phase detection based of the FPGA with an analysis of the main factors that affect the detection accuracy such as jitter, algorithm's defects and non-linearity of devices, which is helpful for future work on high precision detection and control.     

FPGA-based amplitude and phase detection in DLLRF

The new generation particle accelerator requires a highly stable radio frequency（RF） system. The stability of the RF system is realized by the Low Level RF（LLRF） subsystem which controls the amplitude and phase of the RF signal. The detection of the RF signal＇s amplitude and phase is fundamental to LLRF controls. High-speed ADC（Analog to Digital Converter） ,DAC（Digital to Analog Converter） and FPGA（Field Programmable Gate Array） play very important roles in digital LLRF control systems. This paper describes the implementation of real-time amplitude and phase detection based of the FPGA with an analysis of the main factors that affect the detection accuracy such as jitter,algorithm＇s defects and non-linearity of devices,which is helpful for future work on high precision detection and control.     

Generation of broadly tunable picosecond mid-infrared laser and sensitive detection of a mid-infrared signal by parametric frequency up-conversion in MgO:LiNbO3 optical parametric amplifiers

Picosecond optical parametric generation and amplification in the near-infrared region within 1.361-1.656 μm and the mid-infrared region within 2.976-4.875 μm is constructed on the basis of bulk MgO：LiNbO 3 crystals pumped at 1.064 μm.The maximum pulse energy reaches 1.3 mJ at 1.464 μm and 0.47 mJ at 3.894 μm,corresponding to a pumpto-idler photon conversion efficiency of 25%.By seeding the hard-to-measure mid-infrared radiation as the idler in the optical parametric amplification and measuring the amplified and frequency up-converted signal in the near-infrared or even visible region,one can measure very week mid-infrared radiation with ordinary detectors,which are insensitive to mid-infrared radiation,with a very high gain.A maximum gain factor of about 7 脳 10 7 is achieved at the mid-infrared wavelength of 3.374 μm and the corresponding energy detection limit is as low as about 390 aJ per pulse.     

A novel encoder/decoder design scheme utilizing differential detection in OCDMA systems

In this paper, we report the use of differential detection in optical code-division multiple access (OCDMA) systems which use encoders and decoders based on unbalanced codes and utilize bipolar modulation/differential detection to demonstrate a significant improvement in system performance. Differential detection has been reported earlier also requiring a large number of one-chips in the code for (balanced codes) or with unbalanced codes with very long temporal dimensions requiring a large number of delay elements (either the delay lines in the ladder-type structures or the gratings in the multiple fiber gratings) making the encoder/decoder structures. We use single pulse per row codes to design our system and carry out the simulations for showing the results. The improved BER performance is achieved that can be traded for increasing the number of codes. Using optical simulation tool, the OCDMA system has been simulated for four users. The results of this system utilizing differential detection and another system that uses the same coding scheme but employing direct detection, for the same number of interfering users, are shown for comparison. The BER and the power penalty plots are shown for the two systems. Also, it is shown that performance degradation occurs due to the linear and non-linear effects of the fiber medium. The BER worsens more rapidly with link length for direct detection case, whereas for differential detection with an initial improvement of 8 dB, the increase in BER is insignificantly small for a link length of 500 km.     

束流位置监测系统的研制及其在国家同步辐射实验室二期工程中的应用

介绍一种储存环束流位置监测系统的标定装置。这套标定装置是为NSRL二期工程储存环注入段真空盒改造而研制的。系统的标定精度达±0.01mm。该装置已用于新增注入段真空管的束流位置探测器的定标,获得了探头定标值,并根据其拟合和计算结果对注入段真空管进行了筛选,被选中的真空管已装入储存环注入段。