超分辨率活体人眼视网膜共焦扫描成像系统

活体人眼共焦扫描成像系统的分辨率受到人眼像差、数值孔径和探测针孔尺度的限制,本文设计了一套超分辨活体人眼视网膜共焦扫描系统,采用自适应光学技术探测并校正人眼像差,结合光学超分辨技术提高系统分辨率,补偿有限尺度针孔对分辨率的影响,并获得活体人眼的实时、高分辨图像. 关键词： 超分辨 共焦扫描光学显微术 眼科光学 自适应光学     

共聚焦成像系统中探测器对分辨率的影响

基于点扩展函数，推导出共焦系统的成像公式，模拟了探测器尺寸对分辨率的影响，并提出最佳针孔半径.为验证理论分析，设计并建立了一套共焦系统，测量了不同针孔时的轴向响应，并得到了鉴别率板的共焦和离焦像.     

扫描显微系统中各组元对成像的影响

利用光强点扩散函数讨论扫描显微探测系统中各组无形状对成像的影响。由光源和探测器的讨论得出共焦成像术具有最高横向分辨率的结论，阐明共焦系统中透镜（环瞳和方瞳）对成像的影响，并与圆瞳进行比较，得到最佳系统匹配方法。     

荧光共焦扫描系统成像特性的优化

对荧光共焦扫描系统用光强点扩散函数进行傅里变换得到系统三维传递函数的数学模型，并由此求得环形透镜和各种有限大小探测器系统的光学传递函数。用计算机模拟和光学传递九数值计算，分析了采用不同环形透镜及探测器对系统成像特性的影响     

双光子和多光子共焦显微镜的成像理论

对双光子和多光子共焦扫描显微镜的成像理论作了系统的理论分析,导出了双光子和多光子共焦显微镜成像系统的三维点扩散函数和三维光学传递函数,研究结果表明：双光子共焦显微镜比单光子共焦显微镜具有更高的横向分辨率和纵向分辨率,而多光子共焦扫描显微镜又比双光子共焦扫描显微镜具有更高的空间分辨率. 关键词：     

共焦扫描荧光显微镜的信噪比与信息量

在研制用于对厚的生物样品进行光学断层成像的共焦扫描荧光显微镜时，由于成像信号十分微弱及存在很强的多次散射作用，因此杂散光的抑制非常重要，而信噪比、信号背景比就成为决定能否获得高对比度、高分率图像的关键。运用光学信息量的概念，在已有的光学成像系统信息量计算、共焦扫描荧光显微镜信噪比及传递函数计算的基础上，详细分析了共焦扫描荧光显微镜信息量与信噪比等之间的定量关系。该关系表明，为了充分利用共焦扫描荧光显微镜的成像性能，必须选择适当的探测小孔。所得的结果对于共焦扫描荧光显微成像系统的研制有重要的实用价值。     

同轴扫描式实时光刺激系统

为了解决常规选择性激活方法无法与激光扫描共焦显微镜共用扫描光路,难以与成像光路同轴的问题,提出一种同轴扫描式实时光刺激系统,使用现场可编程门阵列控制声光调制器,以调制激光扫描共焦显微镜的成像光源,经成像光路扫描后,刺激输出和成像扫描实现同步;该系统采用Xilinx KC705开发板中现场可编程门阵列集成的外设部件互连标准硬核,采用外设部件互连标准接口将上位机的刺激图像传输到现场可编程门阵列。测试结果表明,所提系统可以满足传输要求,能有效调节光刺激区域。     

并行共焦测量中的并行光源技术综述

并行共焦测量技术的核心是将单点共焦测量变成多点同时扫描测量,从而使共焦测量速度显著提高。本文介绍了共焦测量技术原理,综述了用于并行共焦的并行光源技术,分析了这些方法的优点和不足。结合作者近年来的研究成果,重点阐述了基于微透镜阵列和数字微镜器件(DMD)产生并行光源的新方法。分析和研究了DMD的空间光调制机理,最终建立了一种单光源双光路并行像散共焦测量系统。     

小型化望远式激光共焦扫描显微内窥镜

研制了一种激光共焦扫描显微内窥镜,采用望远式显微内窥光学系统,同时实现长距离的图像中继传输、远心f-theta光学扫描和显微内窥成像功能.二维共焦扫描由双振镜实现,低噪音扫描控制信号由嵌入式系统产生.为实现便携式应用,激光共焦扫描显微内窥镜采用小型化设计方案.首先,体内的显微内窥成像光学系统,外径尺寸为8 mm,工作长度为250.3 mm,可通过标准腹腔镜手术孔进行体内显微内窥成像;其次,采用3 mm通光孔径的小尺寸平面反射镜实现体外共焦扫描,摆动频率为100 Hz,实现快速共焦扫描;最后,激光控制和荧光探测仅通过电缆和光纤与共焦扫描显微内窥镜前端连接,减小了显微内窥镜的前端尺寸和重量.通过实验验证,本系统的成像视场为φ 600 μm,光学分辨率为2.2 μm,可采用手持式或者其他方式工作,进行体内组织的共焦扫描成像,实现微创、在体的荧光显微内窥术.     

反射式光纤共焦扫描成像的研究

建立了反射式光纤共焦扫描成像系统,分析了光纤－集光透镜参数Ａ及物透镜有效数值孔径等对系统成像分辨率的影响。并在此基础上选择了合适参数的透镜,获得了优化的反射式光纤共焦扫描成像系统,测试结果表明,该系统具有亚微米级横向成像能力,微米级向层析能力,成像稳定性那,它将应用于材料及生物组织三维成像检测中。     

X射线同轴相衬成像的参数优化系统

通过对具有2维高斯型相位分布特征的物体的X射线同轴相衬成像技术进行理论分析,建立了成像系统参数优化系统。优化系统明确了图像衬度、信噪比、分辨力和探测器抽样数等成像质量评价参数对射线源能量、源焦斑尺寸、探测器分辨力、成像几何和物体结构特性等系统参数的依赖关系。采用数值模拟,分别对亚微焦点源、激光驱动微焦点源和同步辐射源3种X射线源下的成像系统相关参数进行了优化。结果表明,优化系统很好地完成了系统的优化工作。     

An analysis on radius of curvature aspects of hyperbolic and sinusoidal Gaussian beams

The effective radius of curvature of hyperbolic and sinusoidal Gaussian beams in free space and turbulent atmosphere is studied analytically and numerically. It is shown that the radius of curvature rises with growing source size, and changes slowly with wavelength. In general, given the same source and propagation settings, the beams can be listed in descending order of radius of curvature magnitudes as sinh Gaussian, cosh Gaussian, sine Gaussian, pure Gaussian and cos Gaussian beams. However, the radius of curvature and the difference of the radius of curvature between the different beams reduce with growing strength of turbulence because the beam’s spatial phase distribution is destroyed by turbulence.     

The enhanced backscatter effect with the source and detector at finite distances

Numerical results are presented of double-scatter Kirchhoff calculations for the scattering of light from randomly rough surfaces with the source and detector at finite distances. The surfaces considered are one-dimensional perfectly conducting surfaces and shadowing is included explicitly in the calculations. For the case of the source and detector at the same distance, the scattered intensity distribution is insensitive to the value of this distance except when it is of the order of the surface size. In that case the intensity distribution changes but the backscatter enhancement factor stays constant. For the source and detector at different distances, the backscatter enhancement is less than the enhancement for the case of the source and detector at the same distance.     

远轴高斯波

基于严格求解Helmholtz方程的远场解，提出了一种描述远轴高斯光波传播的新方法．给出了高斯光波振幅、相位分布公式，讨论了光斑尺寸、发散角和能量守恒等关系．并指出任何高斯波的最大光束发散角为65.5°． 关键词：     

Two-proton small-angle correlations in central heavy-ion collisions: A beam-energy- and system-size-dependent study

Small-angle correlations of pairs of protons emitted in central collisions of Ca + Ca, Ru + Ru and Au + Au at beam energies from 400 to 1500MeV per nucleon are investigated with the FOPI detector system at SIS/GSI Darmstadt. Dependences on system size and beam energy are presented which extend the experimental data basis of pp correlations in the SIS energy range substantially. The size of the proton-emitting source is estimated by comparing the experimental data with the output of a final-state interaction model which utilizes either static Gaussian sources or the one-body phase-space distribution of protons provided by the BUU transport approach. The trends in the experimental data, i.e. system size and beam energy dependences, are well reproduced by this hybrid model. However, the pp correlation function is found rather insensitive to the stiffness of the equation of state entering the transport model calculations.     

Propagation properties of Gaussian beams through cat eye optical lens with center shelter

Based on the method of matrix decomposition and expanding the aperture function into a sum of finite complex Gaussian functions, the analytical propagation equations of Gaussian beams through cat eye optical lens with center shelter are derived. Through numerical calculation, the laws governing the variation of the intensity distribution of the cat eye reflected light with the center shelter ratio and the diameter of the detector at the focal plane are given. The results show that the diffraction series and the intensity of the cat eye reflected light depend strongly on the center shelter ratio. As a further extension, it is found that the eye optical lens can be interpreted as a spatial filter, and different filter effect can be obtained by changing the pinhole size.     

Talbot Images of Two-Dimensional Gaussian Beam Arrays with Amplitude Fluctuation

Talbot images constructed in the Fresnel diffraction region due to two-dimensional Gaussian beam arrays with amplitude fluctuation are statistically investigated using a mathematical model based on the propagation law of a Gaussian beam. The average intensity distribution of Talbot images is analyzed theoretically, and the corresponding simulation is conducted by computer. The relative fluctuation of the peak intensity to the mean with respect to Talbot images is found to be less than that of the source by approximately 1/4. Furthermore, the effect of the finite size of source arrays on the formation of Talbot images is revealed throughout the simulation as well as the effect of the amplitude fluctuation.     

Area scintillations of Bessel Gaussian and modified Bessel Gaussian beams of zeroth order

As an extension of our previous study, the area scintillation aspects of Bessel Gaussian and modified Bessel Gaussian beams of zeroth order are investigated. The analysis is carried out on the basis of equal source sizes and equal source powers. It is found that, when compared on equal source size basis, modified Bessel Gaussian beams always have less area scintillations than a Gaussian beam, while Bessel Gaussian beams exhibit more area scintillations. Comparison on equal source power basis, however, removes the advantage of modified Bessel Gaussian beams, that is, their area scintillations become nearly the same as those of the Gaussian beam. On the other hand, for the case of equal source powers, Bessel Gaussian beams with larger width parameters continue to have higher area scintillations than the Gaussian beam. We provide graphical illustrations for profiles of equal source size beams, equal source power beams and the curves to aid the selection of equal source power beams.     

Characteristics of Energy Detection of Quasideterministic Radio Signals

We determine the decision-statistic distribution of an energy detector for the case of receiving an additive mixture of the Gaussian quasi-deterministic signal and Gaussian white noise. Exact and approximate expressions for true detection probability are obtained.     

Secret Key Distillation for Continuous Variable Quantum Key Distribution against Gaussian Classical Eve

The continuous variable quantum key distribution is expected to provide high secret key rate without single photon source and detector, while the lack of the effective key distillation method makes it unpractical under the high loss condition. Here we present a single-bit-reverse-reconciliation protocol against Oaussian classical Eve, which can distill the secret key through practical imperfect error correction with high efficiency. The simulation results show that this protocol can distill secret keys even when the transmission fibre is longer than 150 km, which may make the continuous variable scheme to outvie the single photon one.