大口径电润湿液体透镜

电润湿液体透镜的发展打破了传统变焦系统的种种限制,其优点也越来越受到大家的重视,成为了国内外的热点和重点研究方向。本文提出了一种大口径电润湿液体透镜,采用上下电极组合而成的圆筒形腔体设计,并阐释了其工作原理,同时给出了其制作流程。在研制填充透镜的电润湿液体时,提出了一种对电润湿导电液体分类的模型。本文提出的电润湿液体透镜口径为8 mm,聚一氯对二甲苯介电层厚度为3μm,填充液体密度相同,折射率差为0.1581,并在真空箱中抽取液体中的气泡,以油浸封装的工艺确保透镜密封性。透镜的阈值电压约为60 V,当施加电压为60 V至120 V时,电润湿液体透镜的最小焦距约为-68.73 mm,最大焦距接近无穷,继续增大电压,至200 V时击穿,此时,透镜极限的变倍比为1.8。整个变倍过程中,透镜具有良好的成像质量。     

含弹性与阻尼约束的隔振系统动力学设计

从非线性动力学角度提出一种含弹性和阻尼约束隔振系统的设计方法。该方法先设计满足工作频带内传递率的小阻尼线性隔振系统，再基于对主共振的奇异性理论分析设计约束刚度、约束阻尼和间隙，最后运用周期解延续、插值胞映射等数值方法检验设计的可靠性及各种裕度指标。因靠约束阻尼抑制共振传递率，故工作频带内的传递率可设计得很低。     

Non-redundant Aperture Mask Systems for Interferometric Image Synthesis

A regular procedure is suggested for constructing systems of non-overlapping, non-redundant masks that utilize the entire aperture of a telescope. For a sufficiently large aperture, the mask system covers nearly all of the required domain of spatial frequencies. The method of construction is based on finite-field theory.     

The Intensity Distribution of a Gaussian Schell-model Beam Focused by an Aperture Lens

Abstract

Starting from the generalized Huygens-Fresnel diffraction integral, we study the intensity distribution of a Gaussian Schell-model (GSM) beam diffracted at an aperture lens. A great number of numerical calculations have been performed to illustrate the focused field characteristics. Isophote diagrams are given for systems of different Fresnel numbers, which focus GSM beams, and the related analysis is presented.     

大口径长焦距镜面和透镜的扫描法焦距测量技术

提出了用扫描法测量大口径长焦距镜面或透镜焦距的方法。这种方法是通过对一块Ronchi光栅的Talbot像与另外一个Ronchi光栅所产生的莫尔条纹转角的计量来测量长焦距；通过扫描对大口径范围内的整个区域进行测量。实验结果表明，这种方法能够实时地、非常精确地测量长焦距。     

针尖增强拉曼系统高数值孔径物镜对焦方法研究

为提高针尖增强拉曼系统对焦准确性和效率,提出通过分析CCD相机拍摄的光斑图像的像素值实现自动对焦的方法。首先快速粗调焦缩小调焦范围,然后再慢速细调焦提高调焦精度。实验表明:与Tenengrad评价函数相比,方差评价函数更适用于针尖增强拉曼光谱测量系统自动对焦,聚焦到样品表面时对焦结果的无偏估计标准差<0.25μm,具有较高的重复性和鲁棒性;快速粗调焦可提高调焦效率,避免陷入局部最优解;慢速细调焦评价函数曲线在焦点附近呈现“M”形,可通过二次拟合提高调焦精度。     

Frontal polymerization with encapsulated initiator

Frontal Polymerization (FP) is a process that converts monomers into polymers by means of a propagating spatially localized reaction front. In the simplest case, a mixture of monomers and initiator is placed into a test tube and upon initiation of the reaction at one end of the tube, a self-sustained wave develops and propagates through the tube. Monomer/initiator systems can suffer from a limited pot life, meaning that over a period of time the systems will spontaneously polymerize before they can be used. One way to avoid the undesirable spontaneous polymerization is by microencapsulating the initiator. A mathematical model of nonadiabatic FP waves with encapsulated initiator is presented.     

用于毫米波焦面阵成像系统的扩展半球介质透镜

毫米波成像是近年来毫米波领域的一个研究热点,而焦面阵成像因其具有实时成像的优点更加受到重视。中分析可用为面阵成像的扩展半球介质透镜。这种焦面阵成像结构将集成天线阵贴附在透镜背面接收透镜聚焦的功率,消除了集成天线工作在毫米波频段时存在的表面波对天线性的影响,具有尺寸紧凑、损耗小的特点。采用Stratton-Chu公式和射线追迹分析了电磁波入射到扩展半球透镜上时在其背面的场分布,即透镜的焦区场分布,以获得透镜用于焦面阵成像时的性能。为验证分析方法的正确性,对平面波垂直入射和会聚高斯束入射两种情形进行了实验验证,实验结果与理论分析吻合较好。该透镜天线还可用来消除常规集成毫米波系统中抛物面天线与集成前端之间的过渡,以降低损耗,改善系统性能,也可用于与准光系统的连接或耦合。该结果将对上述应用提供理论指导。     

Multipass System with Large Relative Aperture

Abstract

A six-pass system is proposed aimed at the problems of the high-temperature spectroscopy. As compared to the classical White system, the design under consideration provides twice increased relative aperture at the same transversal size of the cell and uses simple cylindric tubes instead of cells of more complicated shape. The proposed design is the unique multipass system with compensated astigmatism. The system could be recommended for gas analytical device of moderate sensitivity and also for the cells with the fixed path length in the various i.r. spectrometers in particular, in the Fourier-spectrometers.     

Experiments with Lens Optimization Procedures

Some experiments have been carried out to investigate the efficiency of various lens optimization procedures, such as the method of steepest descent, the method of least squares and the method of damped least squares. The results of these experiments demonstrate the efficiency of the damped least squares method. Methods of damping the least squares equations and controlling the boundary conditions are also described and the results of some experiments on these are given.     

Nonlinear Dynamics of Frontal Polymerization with Autoacceleration

A free-boundary model is used to describe frontal polymerization. Autoacceleration effects, such as the gel effect, are accounted for in the formulation. Weakly nonlinear analysis is applied to investigate pulsating instabilities in two dimensions. The analysis produces a pair of Landau equations that describe the evolution of the linearly unstable modes. Autoacceleration influences the linear stability of the system as well as the onset and stability of spinning and standing modes.     

A Numerical Convex Lens for the State-Discretized Modeling and Simulation of Megawatt Power Electronics Systems as Generalized Hybrid Systems

Modeling and simulation have emerged as an indispensable approach to create numerical experiment platforms and study engineering systems. However, the increasingly complicated systems that engineers face today dramatically challenge state-of-the-art modeling and simulation approaches. Such complicated systems, which are composed of not only continuous states but also discrete events, and which contain complex dynamics across multiple timescales, are defined as generalized hybrid systems (GHSs) in this paper. As a representative GHS, megawatt power electronics (MPE) systems have been largely integrated into the modern power grid, but MPE simulation remains a bottleneck due to its unacceptable time cost and poor convergence. To address this challenge, this paper proposes the numerical convex lens approach to achieve state-discretized modeling and simulation of GHSs. This approach transforms conventional time-discretized passive simulations designed for pure-continuous systems into state-discretized selective simulations designed for GHSs. When this approach was applied to a largescale MPE-based renewable energy system, a 1000-fold increase in simulation speed was achieved, in comparison with existing software. Furthermore, the proposed approach uniquely enables the switching transient simulation of a largescale megawatt system with high accuracy, compared with experimental results, and with no convergence concerns. The numerical convex lens approach leads to the highly efficient simulation of intricate GHSs across multiple timescales, and thus significantly extends engineers’ capability to study systems with numerical experiments.     

Influences of Detection Pinhole and Sample Flow on Thermal Lens Detection in Microfluidic Systems

Thermal lens microscopy (TLM), due to its high temporal (\({\sim }\mathrm{ms}\)) and spatial resolution (\({\sim }\upmu \mathrm{m}\)), has been coupled to lab-on-chip chemistry for detection of a variety of compounds in chemical or biological fields. Due to the very short optical path length (usually below 100 \(\upmu \mathrm{m}\)) in a microchip, the sensitivity of TLM is unfortunately still 10 to 100 times lower than conventional TLS with 1 cm sample length. Optimization of the TLM optical configuration was made with respect to different pinhole aperture-to-beam size ratios for the best signal-to-noise ratio. In the static mode, the instrumental noise comes mainly from the shot noise of the probe beam when the chopper frequency is over 1 kHz or from the flicker noise of the probe beam at low frequencies. In the flowing mode, the flow-induced noise becomes dominant when the flow rate is high. At a given flow rate, fluids with a higher density and/or a higher viscosity will cause larger flow-induced noise. As an application, a combined microfluidic flow injection analysis (\(\upmu \mathrm{FIA}\))–TLM device was developed for rapid determination of pollutants by colorimetric reactions. Hexavalent chromium [Cr(VI)] was measured as a model analyte. Analytical signals for 12 sample injections in 1 min have been recorded by the \({\upmu }\)FIA–TLM. For injections of sub-\(\upmu \)L samples into the microfluidic stream in a \(50\,\upmu \mathrm{m}\) deep microchannel, a limit of detection of \(4\,\mathrm{ng}{\cdot }\mathrm{mL}^{-1}\) was achieved for Cr(VI) in water at 60 mW excitation power.     

Coded Aperture Imaging

We have simulated the performance of various apertures used in coded aperture imaging—optically. The annulus, twin annulus, Fresnel zone plate and the uniformly redundant array have been decoded using a non-coherent correlation process. Ways of reducing the ‘d.c.’ background of the various apertures are discussed. Results of imaging extended and continuous-tone planar objects are presented.     

On Arbitrarily Perfect Imagery with a Finite Aperture

In theory, an optical system with a finite aperture can be coated to produce arbitrarily perfect imagery over a limited field. When the object is of limited extent, this field can be made the optical conjugate to the object, so that the whole object is imaged with arbitrary precision. The required pupil coating approximates low-contrast cosine fringes over its central region, with a frequency and amplitude that rapidly accelerate as the aperture edge is approached. Here the maximum occurs as a narrow spike. The frequency near the central region varies directly with the total extent of the conjugate field, and inversely with the required central core width Δ in the point amplitude response. As Δ is made arbitrarily narrow, the point amplitude response approaches the form of a sinc function over the field of view. This function is precisely the point amplitude for a diffraction-limited pupil with a magnified aperture of 1/Δ times the given pupil aperture ! The only image property that is not in compliance with this effective aperture magnification is that of total illumination. This is severely reduced from that of the original, uncoated aperture, and is the major restriction on practical use of the derived pupil. Applications to microscopy and telescopy are discussed.     

Nonadiabatic Frontal Polymerization

Frontal polymerization is a process in which a spatially localized reaction zone propagates into a monomer, converting it into a polymer. In the simplest case of free-radical polymerization, a mixture of a monomer and initiator is placed into a test tube. Upon reaction initiation at one end of the tube a self-sustained thermal wave, in which chemical conversion occurs, develops and propagates through the tube. In a previous paper, a perfectly insulated tube (i.e., an adiabatic polymerization process) was considered. In reality, it is nearly impossible to eliminate heat losses completely, and an accurate model must take this into account. Extinction of polymerization waves and difficulties initiating the wave, both as a result of heat losses, are often encountered in experiments. This paper will therefore concentrate on nonadiabatic frontal polymerization. The propagation of nonadiabatic free-radical polymerization fronts is studied by methods originally developed in combustion theory, and employed in a previous paper. This analysis is accomplished by examination of the structure of the polymerization wave, its propagation velocity, degree of conversion of the monomer and maximum temperature, and how these quantities are affected by changes in initial temperature, concentrations and kinetic parameters. The values of these quantities near the extinction limit (beyond which traveling-wave solutions will no longer exist) are compared to those in the adiabatic case.     

复合静电-磁浸没透镜的宽束曲轴聚焦性质及像差理论

研究了新型的复合静电 磁浸没透镜的曲光轴高斯电子光学性质及像差特性。应用宽束曲轴理论 ,导出了三维局部正交坐标系中的电子运动的中心轨迹方程和曲光轴的近轴轨迹方程 ;利用数学软件Mathematica推导出了复合静电 磁浸没透镜全部曲轴二级像差系数。作为实例 ,文中针对轴上磁场和电场具有某种解析表达式的旋转对称的静电 磁浸没透镜系数 ,计算了它的曲轴高斯聚焦特性和二级像差 ,并给出了二级像差分布图形     

用于纳米光刻的超分辨缩小成像平板超透镜研究

本文提出和研究了利用超分辨缩小成像平板超透镜,在i线光源波长下实现纳米尺度光刻方法.为了在超 分辨透镜像面位置获得高质量的光刻图形,采用超分辨透镜-光刻胶-反射银膜的结构方式,解决由于超透镜磁场偏振传输模式带来的成像光场畸变问题,大大提高了成像质量和光场对比度.采用掩模图形结构预补偿的方法,消除超分辨透镜的倍率畸变像差...     

一类含间隙系统的分岔与混沌的形成过程

用变步长四阶Runge-Kutta法,通过对一类单自由度含间隙系统一组系统参数的仿真,首次证明了单自由度含间隙系统中不仅存在叉式分岔、倍周期分岔,而且还存在Hopf分岔,并且给出了发生Hopf分岔的具体系统参数以及Hopf分岔与混沌的形成过程。对其分岔与混沌行为的研究为工业实际中含间隙机械系统和冲击振动系统的优化设计提供了理论依据。