利用可变形镜进行像差校正研究

利用可变形镜对光学系统某一视场角像差进行单独动态校正.系统中使用可变形镜将全视场内某一特定视场角的像差校正到衍射极限水平,该区域在整个视场内动态高速地改变来对视场内任意区域进行高分辨率成像.利用这种技术可实现光学系统的小型化、轻型化,减小系统的体积,同时由于实现变分辨率成像,数据量大大减少,降低了数据传输对带宽的要求.     

利用可变形镜进行像差校正研究

利用可变形镜对光学系统某一视场角像差进行单独动态校正．系统中使用可变形镜将全视场内某一特定视场角的像差校正到衍射极限水平,该区域在整个视场内动态高速地改变来对视场内任意区域进行高分辨率成像．利用这种技术可实现光学系统的小型化、轻型化,减小系统的体积,同时由于实现变分辨率成像,数据量大大减少,降低了数据传输对带宽的要求．     

后向动态光散射系统的像差分析与校正

针对后向动态光散射颗粒测量系统信噪比较低的问题,从光学系统的像差入手,采用Zemax对其进行了仿真和分析,并提出了校正方案。首先介绍了后向动态光散射颗粒测量系统的基本原理和光学系统,从校正像差的角度出发,采用Zemax对后向动态光散射系统进行仿真,并对其像差进行分析。然后根据仿真结果,提出了校正方案,采用Ze-max设计了方案中的参数,得出了理论上的校正结果。最后采用优化好的结果进行后向动态光实验,得到了实验数据。均值误差和重复性误差分别达到了1.52%和1.24%。满足国标均值误差和重复性误差小于2%的要求。     

自由曲面校正光学系统像差的研究EI北大核心CSCD

利用条纹泽尼克多项式来表征自由曲面的光学元件,并将多项式中表示初级球差、彗差、像散项转换为矢量形式.利用矢量波像差理论,研究了自由曲面光学元件校正光学系统初级像差的特性.通过分析可知,自由曲面在光学系统中不同位置时所校正的像差特性不同.当自由曲面位于光学系统的孔径光阑(入瞳或出瞳)上可以校正光学系统全视场内为常数的初级像差;当自由曲面远离孔径光阑时,由于轴外视场成像光束口径的缩放与偏移,自由曲面可以校正非对称初级像差,且不同初级像差与视场依据关系不同.     

基于Zernike模型系数优化的椭球型窗口光学系统像差校正

传统的半球形窗口难以满足高速飞行器气动力学的需求,采用流线型外表面的非球面光学窗口技术应运而生.这种窗口会随着扫描视场角的变化产生大量动态像差,校正这类像差成为高速飞行器光电成像系统发展的关键问题.对于扫描视场为±60°的椭球形窗口光学系统,研究了静态校正和无波前探测器的自适应光学技术相结合的大扫描视场像差校正方法.设计时,首先以减少系统像差种类为导向,进行初始结构设计,消除五阶Zernike像差,从而减少后续自适应优化控制变量数.利用Zernike多项式系数与变形镜驱动器电压之间的转换矩阵,将优化变量由140个驱动器电压减少至Zernike多项式2—9项系数.最后利用基于Zernike模型的遗传算法对变形镜面形进行控制,校正残余像差.仿真结果表明,各典型扫描视场点的优化速度提升95%以上,且光学像质接近衍射极限.该优化方法不仅可以修正异形光学窗口引起的像差,同时还能够校正光学系统装调、加工时引起的误差,具有较强的实用性.     

基于星点像重采样的星敏感器高精度质心算法

传统的质心算法面临着光学像差和随机噪声对质心位置提取精度影响很难减小的问题。为了解决这一问题,对星敏感器所成星点像进行分析,结合星敏感器光学系统的调制传递函数和图像传感器像素频率响应特性,提出了一种基于星点像重采样的星敏感器质心定位算法。根据夫琅禾费衍射理论计算出离焦光学系统的点扩展函数,并对重采样质心算法的系统误差分布进行仿真,结果显示,该算法在不同像差条件下的系统误差均方根都小于0.01 pixel。用星敏感器产品进行了质心提取系统误差测量实验,重采样质心算法的系统误差为0.008 pixel,相比传统正弦曲线补偿方法的精度提高了66%。仿真和实验结果表明:基于星点像重采样的质心算法精度高,受光学系统像差的影响小,是提高星敏感器测量精度的一种有效方法。     

基于固定校正板和透镜阵列的机载共形窗口像差校正

为了校正大扫描视场机载共形窗口引入的像差,提出一种基于固定校正板和透镜阵列的静态校正方法。首先使用固定校正板校正静态像差;然后在像面前安置固定的透镜阵列,利用透镜阵列中的各个透镜单元分别校正不同扫描角度的动态像差;最后基于所提方法设计应用在机载共形光学系统中的像差校正器。设计结果表明,所提方法在±42°的扫描视场范围内能够良好地校正共形窗口引入的像差。与其他动态或静态校正方法相比,所提方法可以实现大扫描视场机载共形光学系统像差的校正,同时降低机载共形光学系统的质量,提高系统的稳定性。     

基于双波前传感器自适应光学技术的太阳光栅光谱仪

为了研究不同太阳大气高度的热力学特性,具有良好成像质量的成像型光栅光谱仪是实现这个目标的重要仪器。然而作为地基式太阳望远镜重要的终端仪器之一,光栅光谱仪的光谱成像性能不可避免的会受到动态波前像差和系统静态像差的影响。动态波前像差常通过在太阳望远镜系统中集成自适应光学系统进行补偿。针对光学系统中的由装调和光学元件加工等引起的静态波前像差,提出了一种基于自适应光学技术校正光栅光谱仪中静态波前像差的方法,并进行了数值模拟仿真和实验验证。实验结果表明,校正后系统的残余波前像差RMS≈0.025λ,此时波前像差对光谱分辨率和能量利用率的影响可忽略,提高了光栅光谱仪的光谱成像质量,证明了所提出的方法的有效性。此外它具有降低光学系统装调精度和光学元件加工精度要求的优点。     

SPGD算法高精度静态像差校正方法

随机并行梯度下降（SPGD）算法广泛应用于光学系统静态像差校正,其性能指标对校正效果影响较大。由于传统的环围能量（EE）校正精度低、平均半径（MR）稳定性差,提出性能指标组合法,以实现静态像差的高精度、稳定校正。所提方法将EE与MR性能指标相结合进行像差校正,首先以EE作为性能指标对畸变图像进行校正,待能量集中于环围区域后,利用MR性能指标继续进行校正,直至能量分布均匀,校正终止。首先进行了校正仿真,结果显示：相比于EE和MR方法,性能指标组合法对静态像差的校正精度高、稳定性好。搭建实验光路,验证了所提方法的有效性。模拟和实验结果均表明,采用性能指标组合法可以获得高的校正精度且校正稳定。该方法可以应用于光学系统静态像差的校正和消除,实现其接近衍射极限的光学性能。     

基于小孔光阑的CCD过饱和像差分析方法

如何比较全面、准确地观测和分析光学系统的几何像差一直是光学以及光学设计领域中的一个重大问题.本文提出了一种观测和分析光学系统像差的新方法——基于小孔光阑的CCD过饱和分析方法,以激光为照明光源采用开放式的光路搭建,利用定标孔阑划分波带并结合CCD过饱和的分析手段.该方法具有原理易懂、操作简单、图样信息丰富、现象明显直观、成本低廉等优点,不仅为分析和观测光学系统的几何像差提供方便,同时也为光学系统的相关研究提供借鉴.     

A wavefront aberrometer for dynamic high-order aberration measurement

This research studied the dynamic aberration of human eyes at near vision. A wavefront aberrometer was developed based on the Hartmann-Shack theory. This aberrometer can achieve dynamical aberration measurement of the human eye. The Aberrometer induces ocular accommodation by a moving target at near vision, and records the vision information of human eyes simultaneously during ocular accommodation process using a Hartmann-Shack sensor. Nineteen eyes of 10 volunteers are tested. Eighty-four percent eyes have induced accommodation amplitude between 3 diopter (D) and 8D. The highest induced accommodation amplitude is 8.6D. The aberrometer produces results with high precision and repeatability, i.e. an accuracy root-mean-square (RMS) of 1/50^λ and a repeatability RMS of 1/500^λ.     

Dynamic nuclear polarization system for the SANS-J-II spectrometer at JAEA

We have developed a dynamic nuclear polarization (DNP) system for the SANS-J-II spectrometer at the JRR-3 atomic research reactor of Japan Atomic Energy Agency (JAEA). The DNP system is composed of a split-type horizontal superconducting magnet (3.3 T), a Gunn oscillator as a microwave source (94 GHz), and a cryostat (1.2 K). In particular, a sample cell with 40 in inner diameter and the magnet with a field homogeneity of 5×10⁻⁵ in a volume of 25 mm×8 mm were employed to polarize samples with a diameter of 20 mm for the ultra small-angle scattering experiment using the magnetic lens installed at the SANS-J-II spectrometer [S. Koizumi, H. Iwase, J. Suzuki, T. Oku, R. Motokawa, H. Sasao, H. Tanaka, D. Yamaguchi, H.M. Shimizu, T. Hashimoto, J. Appl. Crystallogr. 40 (2007) s474]. We obtained the proton polarization |P|=32% in the polyethylene doped with 2,2,6,6-tetra-methyl-piperidine-1-oxyl (TEMPO).     

Dynamic Entanglement and Separability Criteria for Quantum Computing Bit States

A theoretical framework is demonstrated to evaluate the degree of entanglement of bit states in quantum computing. Separability of general superposition of Hilbert space unit vectors is discussed, and criteria in amplitude as well as in phase are derived. By these criteria the possibility of different quantum gates such as controlled not (CN), controlled controlled not (CCN), controlled rotation (CR), and controlled phase shift (CPS), to create the entanglement is examined. Furthermore, the selection of measurement mode external to the quantum system is incorporated in the formula using Kronecker delta (δ _kx ), introducing the concept of dynamic entanglement. With this the process of wavefunction collapse upon measurement is understood as the result of the activation of the dynamic entanglement. A firefly in a box model is used to show a pure state of ontological uncertainty, which is in a dynamically entangled state in Hilbert space.     

Dynamic exchange-correlation potentials for the 2D electron gas

Recent progress in the formulation of a fully dynamical local approximation to time-dependent density functional theory (TD-DFT) appeals to the longitudinal and transverse components of the long-wavelength exchange and correlation kernel in the homogeneous electron gas, . We extend to the two-dimensional longitudinal and transverse case our work on the 3D [J. Phys.: Condens. Matter 9 (1997) 475], which accounts for two-pair excitations through an approximate decoupling of the equation of motion for the current–current response function. We present numerical results and compare with asymptotic behaviours and previous approximations.     

Dynamic peer-to-peer competition

The dynamic behavior of a multiagent system in which the agent size s_i is variable it is studied along a Lotka-Volterra approach. The agent size has hereby the meaning of the fraction of a given market that an agent is able to capture (market share). A Lotka-Volterra system of equations for prey-predator problems is considered, the competition factor being related to the difference in size between the agents in a one-on-one competition. This mechanism introduces a natural self-organized dynamic competition among agents. In the competition factor, a parameter σ is introduced for scaling the intensity of agent size similarity, which varies in each iteration cycle. The fixed points of this system are analytically found and their stability analyzed for small systems (with n=5 agents). We have found that different scenarios are possible, from chaotic to non-chaotic motion with cluster formation as function of the σ parameter and depending on the initial conditions imposed to the system. The present contribution aim is to show how a realistic though minimalist nonlinear dynamics model can be used to describe the market competition (companies, brokers, decision makers) among other opinion maker communities.     

Dynamic analytical model for charge transport in octithiophene thin film transistors

In this paper, we develop a device model of an organic thin film transistor (OTFTs) in which the active layers are made of octithiophene. This model is based on variable range hopping theory, i.e., a carrier may either hop over a small distance with a high activation energy or hop over a long distance with a low activation energy. The model takes into account all the operating regimes in direct current and transient mode; the transistor symmetry is also considered. The model has been developed using a physical basis where the model parameters can easily be extracted. The current–voltage characteristics of short-channel organic TFTs have been calculated starting from the solution of the drain current equation for an enhancement mode p-channel MOSFET. A good agreement between theory model and experimental results is obtained. Different transport parameters are extracted by using a fitting method. We have extracted the mobility of charge in saturation regime using differential method. Based on first and second derivative of transfer characteristic we extracted a serial resistance, intrinsic mobility and threshold voltage. The mobility in saturation regime is reproduced using the VRH model. Finally, we give a simple small-signal equivalent circuit.     

全光网络中动态业务下的阻塞性能分析

通过对自适应路由和动态备选路由算法的性能分析,研究了波长选择和波长交换这两种类型的全光网络在动态业务下的阻塞性能,并提出了将动态波长分配与自适应路由选择相结合的算法.数值结果表明:1)相比波长交换网络而言,多纤波长选择网络是更为经济且切实可行的选择;2)动态备选路由算法可以获得与自适应路由算法相似的性能,并且文中所提出的算法能够更好的提高网络的阻塞性能.分析表明:不同算法的性能与网络拓扑的连接度以及备选路由的数目密切相关.     

LNG液化装置冷箱降温过程的动态模拟

冷箱的降温是MRC天然气液化装置运行调试过程的重点。文中对此过程进行了动态仿真,除降温后期偏差稍大外,结果基本令人满意。冷箱降温前期中期主要受冷箱本身的显热容影响,而后期降温过程主要取决于冷箱的换热能力。     

后向动态光散射测量中样品池的影响及校正

针对后向动态光散射高浓度颗粒测量中样品池产生的影响,本文对负球差进行了分析,提出了采用ZEMAX确定聚焦透镜的光学参数校正球差的方案,对由于样品池表面反射引起的二次散射进行计算,提出了削弱二次散射的方法。     

Dynamic Spectrum for noninvasive blood component analysis and its advances

Noninvasive blood component analysis by spectroscopy has broad prospects that based on Dynamic Spectrum (DS) can effectively suppress the influences of individual differences (such as skin, muscle, fat) and the variations of measurement conditions, which shows its potential in the clinical applications. The purpose of this article is to review the starting point and the advances of DS, to assess the current situation of the field and to explore future directions. The principle of DS and the error sources of noninvasive blood component analysis were introduced. An overview of the six stages of noninvasive blood component analysis, including sensing principle, acquisition methods of spectral photoplethysmography (photoplethysmography signal at multiple wavelengths) signals, spectral photoplethysmography (SPPG) preprocessing, DS extraction methods from SPPG, the quality evaluation for DS and modeling methods, was presented. Finally, the existing issues of DS are discussed and the future directions are predicted.