基于Supporting-Ellipsoid方法的自由曲面构造

为了在特定平面上获得任意形式的辐照分布,采用了Supporting-Ellipsoid设计方法来构造自由曲面反射镜。介绍了其设计思想和设计过程,并以具体的设计实例为例构建了自由曲面光学系统。仿真结果表明,在不计反射损失的情况下,系统效率达到了97%,较传统太阳模拟器光学系统提升了3倍以上,不均匀度达到5.26%,与理想状态有一定差距,这是因为设计中兼顾了计算时间和自由曲面光滑性所造成的。     

基于遗传算法的自由曲面优化设计

为解决传统点光源近似设计方法难以满足实际应用需求的问题,基于遗传算法提出了一种面向扩展光源的自由曲面优化设计方法.该方法以虚拟点光源的辐射分布函数、原点位置偏移量及目标面尺寸因子等参数作为优化对象,首先对种群中任意个体根据能量守恒定律及Snell定律建立并求解偏微分方程,得到对应于该组虚拟参数的自由曲面,然后以实际扩展光源进行光线追迹,并综合考虑目标面照度均匀度和系统传输效率得到个体适应度,据此对种群进行选择、交叉和变异,直至优化结果满足设计要求.设计了发散半角为10°的均匀照明系统,光源采用直径为30mm的圆盘朗伯源,在Trace/pro环境下与传统设计方法进行对比,结果表明:系统均匀度从58.3%提高到93.5%,辐射传输效率从61.8%提高到72.9%,且光束质量对目标面距离的变化具有很好的稳定性.该设计方法能较好地实现对扩展光源辐射在空间分布的调控,对扩展光源系统设计具有重要指导意义.     

基于子曲面分割和迭代的自由曲面光线追迹方法

根据光学自由曲面数学描述复杂,但面形较为平滑的特点,提出一种新的基于子曲面分割和迭代的自由曲面光线追迹方法。通过离散点分割形成子曲面阵列,根据三角形内角和定理确定目标子曲面,对目标子曲面进行切平面迭代完成光线追迹。通过数值仿真,采用所提方法分别对偶次非球面、双圆锥曲面、扩展多项式面和单透镜无像散系统进行光线追迹,并与ZEMAX追迹结果进行比对。结果表明:该方法在离散点采样密度很低的情况下（降低了计算机的内存消耗和运算时间）仍然可以保证光线追迹的精确性,与ZEMAX中光线和自由曲面交点的偏差达到10-3（nm）量级,出射光线角度的偏差达到10-3（）量级。     

基于EtherCAT的并联六自由度平台设计

摘要：在设计六自由度运动平台时,运动精度是重要的评价指标,为了能够降低位姿跟踪误差并提高各轴的协同控制,在对平台进行位姿正反解的基础上,设计了一套基于EtherCAT总线的六自由度运动平台,通过EtherCAT网络进行数据帧的快速传输。系统硬件由工控机、EtherCAT网络、伺服电机、Stewart型平台构成,系统软件则采用VC++进行上位机界面的开发,由TwinCAT进行下位机控制程序的开发,通过电子凸轮实现平台各轴的同步控制,其中上下位机通过ADS进行通讯。由实验结果可知,六自由度平台平移跟踪误差小于0.04mm,转动跟踪误差小于0.01°,静态定位精度优于0.1%,达到预定的控制要求。基于EtherCAT的六自由度平台具有良好的同步性能和位姿精度,也表明EtherCAT在多轴同步伺服控制上具有较好的响应速度和控制精度。     

基于加工公差约束的自由曲面棱镜设计

自由曲面棱镜是轻型头盔显示系统的核心光学器件,其巧妙的设计以及精密的加工方法历来备受研究者的关注。目前有关自由曲面棱镜的研究主要集中于视场角和成像质量上,而忽略了公差设计,尤其是加工误差对棱镜的影响。针对这一现象,在详细分析了自由曲面棱镜的加工误差来源之后,提出了基于公差约束的自由曲面棱镜优化设计方法,以保证在加工精度允许的前提下得到最佳的成像质量。通过光学仿真实验及成像质量分析,验证了该方法的有效性。     

基于自由曲面的高倍率广角显微目镜设计

随着显微镜性能的不断提升,要求显微目镜具有更大的视场、放大倍率以及更好的成像质量.显微目镜由于孔径光阑外置,且焦距较短,其设计难点在于如何校正大视场带来的畸变与其他轴外像差,并在此基础上获得符合人眼观察要求的出瞳距离.本文分析了目镜光学系统存在的主要像差,特别是带有畸变的光学系统对成像所产生的影响.将自由曲面应用在显微目镜光学系统畸变校正中,设计出一款视场角达到60°(即±30°),放大倍率达到25×且全视场畸变小于5%的高倍率广角显微目镜.采用五片三组元式结构,其中自由曲面镜片采用塑料材料且关于XOZ与YOZ平面对称,实现了结构简单、易于加工且成本较低的高性能显微目镜设计.     

基于自由曲面的光纤照明用耦合透镜设计

提出一种基于自由曲面的光纤照明用耦合透镜的设计方法。通过非成像光学设计,以光学扩展量与折射定律为理论基础,自由曲面迭代优化,实现光源与光纤之间的低损耗耦合。仿真结果表明:以LED芯片作为光源,该透镜可以将光通量传导效率提高至89%以上,具有良好的应用和发展前景。     

支撑曲面法设计自由曲面照明透镜

利用能量守恒建立光源与目标之间的网格映射可以用来设计自由曲面照明透镜,然而这种方式设计透镜表面的连续性依赖于映射是否可积。其根本原因是这种预先设定的映射并非照明问题的真实解。为了得到连续的透镜曲面,首先使用支撑曲面法利用一定数量的笛卡尔卵形面构造非连续的自由曲面透镜。以这个透镜为初始设计,通过拟合建立光源与目标面的网格映射。由于初始设计的透镜为照明问题的真实解,因此这个映射满足可积条件。光学仿真表明这种方法设计的透镜可以在目标面达到目标面达到0.77的照度均匀性以及81.6%的光学效率,同时透镜的表面连续。     

基于自由曲面的产生五向准直光束的元件

为了实现光束沿多向准直出射的要求,提出了基于自由曲面的光学器件设计方法。该光学器件是四个侧面为自由曲面、上表面为准直透镜的空心梯形台。基于微分几何理论和折射定律,建立梯形台侧面轮廓曲线上的点所满足的方程,结合Matlab软件数值计算出自由曲面轮廓曲线的离散数据点,将数据点导入Solidworks中进行曲线拟合并建模,进而得到梯形台侧面的实体模型;运用CodeⅤ软件设计出上表面准直透镜。将自由曲面面型数据和准直透镜数据导入到Lighttools软件中进行了仿真模拟,结果表明,该光学器件可实现光线五向准直出射。     

自由曲面光学系统设计及其应用

介绍了自由曲面光学系统研究背景,自由曲面描述方法,光学设计中的逐步逼近优化和像质自动平衡优化两种算法。并以实际应用中的头盔光学系统设计及大视场、高分辨率头盔显示器的设计为例对这些方面进行分析,讲解了自由曲面光学系统设计及其应用。     

基于Marangoni界面效应的数控化学抛光去除函数的研究

 利用基于Marangoni界面效应对化学抛光去除函数的理论及实验进行研究,提出采用湿法化学抛光（刻蚀）方法为大口径高精度光学元件的加工提供新的解决途径。介绍了Marangoni界面效应及其验证实验,运用WYKO轮廓仪对熔石英基片局域刻蚀前后的粗糙度进行检测,结果表明,粗糙度基本无变化,刻蚀前后粗糙度分别为0.72 nm和0.71 nm。基于Preston假设, 建立了数控化学抛光理论模型,运用WYKO干涉仪观察实验现象可知,化学抛光刻蚀曲线基本上成平底陡峭的去除函数曲线,小磨头抛光是倒置的仿高斯函数曲线。     

基于Marangoni界面效应的数控化学抛光去除函数的研究

利用基于Marangoni界面效应对化学抛光去除函数的理论及实验进行研究,提出采用湿法化学抛光（刻蚀）方法为大口径高精度光学元件的加工提供新的解决途径。介绍了Marangoni界面效应及其验证实验,运用WYKO轮廓仪对熔石英基片局域刻蚀前后的粗糙度进行检测,结果表明,粗糙度基本无变化,刻蚀前后粗糙度分别为0.72 nm和0.71 nm。基于Preston假设, 建立了数控化学抛光理论模型,运用WYKO干涉仪观察实验现象可知,化学抛光刻蚀曲线基本上成平底陡峭的去除函数曲线,小磨头抛光是倒置的仿高斯函数曲线。     

Correction of small imperfections on white glazed china surfaces by laser radiation

A laser-assisted technique has been developed for correction of small diameter (1 mm) and shallow (0.5 mm) imperfections on the surface of gloss fired porcelain. To study the physics and establish the important parameters, artificially made holes in a porcelain sample have been first filled with correction material, then covered with raw glaze and treated by a pulsed, 7 kHz repetition rate CO₂ laser at 10.6 μm. The modification of the surface and the surrounding area have been quantified and studied with a large range of parameters of incident laser power (1-10 W), width of the laser pulses (10-125 μs) and duration of laser heating (60-480 s). Although the shine of the treated area, defined as the distribution of micro-droplets on the surface, is very similar to the untreated surfaces, the surroundings of the treated area usually show cracks. The measurement of both the spatial temperature distribution and the temporal cooling rate of the treated surface has revealed that a simple melting process always results in high gradient temperature distribution within the irradiated zone. Its inhomogeneous and fast cooling always generate at least micro-cracks on the surface within a few seconds after the laser was turned off. The duration and intensity of the laser irradiation have been then optimized in order to achieve the fastest possible melting of the surface, but without producing such high temperature gradients. To eliminate the cracks, more elaborated pre-heating and slowed-cooling-rate processes have been tried with prosperous results. These achievements complete our previous study, making possible to repair the most common surface imperfections and holes of gloss fired china samples.     

Effects of the ultrasonic flexural vibration on the interaction between the abrasive particles; pad and sapphire substrate during chemical mechanical polishing (CMP)

In this paper, the technique of ultrasonic flexural vibration assisted chemical mechanical polishing (UFV-CMP) was used for sapphire substrate CMP. The functions of the polishing pad, the silica abrasive particles, and the chemical additives of the slurry such as pH value regulator and dispersant during the sapphire's UFV-CMP were investigated. The results showed that the actions of the ultrasonic and silica abrasive particles were the main factors in the sapphire material removal rate (MMR) and the chemical additives were helpful to decrease the roughness of sapphire. Then the effects of the flexural vibration on the interaction between the silica abrasive particles, pad and sapphire substrate from the kinematics and dynamics were investigated to explain why the MRR of UFV-CMP was bigger than that of the traditional CMP. It indicated that such functions improved the sapphire's MRR: the increasing of the contact silica particles’ motion path lengths on the sapphire's surface, the enhancement of the contact force between the contact silica particles and the sapphire's surface, and the impaction of the suspending silica particles to the sapphire's surface.     

Fabrication of superhydrophobic surfaces based on ZnO-PDMS nanocomposite coatings and study of its wetting behaviour

Superhydrophobic surfaces based on ZnO-PDMS nanocomposite coatings are demonstrated by a simple, facile, time-saving, wet chemical route. ZnO nanopowders with average particle size of 14 nm were synthesized by a low temperature solution combustion method. Powder X-ray diffraction results confirm that the nanopowders exhibit hexagonal wurtzite structure and belong to space group P63mc. Field emission scanning electron micrographs reveal that the nanoparticles are connected to each other to make large network systems consisting of hierarchical structure. The as formed ZnO coating exhibits wetting behaviour with Water Contact Angle (WCA) of ∼108°, however on modification with polydimethylsiloxane (PDMS), it transforms to superhydrophobic surface with measured contact and sliding angles for water at 155° and less than 5° respectively. The surface properties such as surface free energy (γ_p), interfacial free energy (γ_pw), and the adhesive work (W_pw) were evaluated. Electron paramagnetic resonance (EPR) studies on superhydrophobic coatings revealed that the surface defects play a major role on the wetting behaviour. Advantages of the present method include the cheap and fluorine-free raw materials, environmentally benign solvents, and feasibility for applying on large area of different substrates.     

Toward a description of reactions of CO and H2 on Fe surfaces based on SCF hybrid AOs and electronegativity equalization

Maximum localization hybrids and electronegativity equalization have been used to obtain a simple reliable SCF picture of directional and charge-transfer effects determining the state and reactivity of CO adsorbed on iron. The hybridization procedure has been applied to H₂ adsorbed on FeCO, so as to describe the evolution of the complex toward a final geometry, which corresponds to a possible chemisorbed =CH−OH species, with the CO bond strongly inclined toward the surface. Abbiamo usato ibridi di massima localizzazione e la condizione di uguaglianza delle elettronegatività per ottenere una descrizione semplice e al tempo stesso affidabile degli effetti direzionali e di trasferimento di carica che determinano lo stato e la reattività del CO adsorbito su ferro. Il procedimento di ibridazione è stato applicato a H₂ adsorbito su FeCO in modo tale da descrivere l'evoluzione del complesso verso una geometria finale, la quale corrisponde ad una possibile specie chemisorbita =CH−OH, in cui il legame CO è fortemente inclinato verso la superficie. Используются смешанные состояния с максимальной локализацией и уравнивание электроотрицательности для получения простой SCF картины для ориентационных эффектов и эффектов переноса заряда, которые определяют состояние и реактивность адсорбированного CO на железе. Применяется процедура гибридизации к адсорбированной молекуле H₂ на FeCO. Описывается эволюция комплекса в сторону конечной геометрии, которая соответствует возможной группе =CH−OH с связью CO, которая сильно наклонена по отношению к поверхности.     

Improving the sensitivity of a humidity sensor based on fiber bend coated with a hygroscopic coating

A highly sensitive all-fiber humidity sensor is demonstrated. The sensor behaves as a humidity dependent optical switch between 85% and 90% RH. This sensor also offers the advantages of simple structure and low cost and its response is fast and reversible in nature. The typical humidity response of the sensor is suitable for using it as a human breath rate monitor.     

Incomplete similarity of a plane turbulent wall jet on smooth and transitionally rough surfaces

This study assesses the hypothesis of incomplete similarity for a plane turbulent wall jet on smooth and transitionally rough surfaces. Typically, a wall jet is considered to consist of two regions: an inner layer and an outer layer. The degree to which these two regions reach equilibrium with each other and interact to produce the property of self-similarity remains an open question. In this study, the analysis of the outer and inner regions indicates that each region is characterised by a half-width which exhibits its own distinct dependence on the streamwise distance x from the slot, and a single self-similar structure for both regions does not exist. More specifically, the inner and outer layers of the wall jet exhibit different scaling laws, which results in two self-similar mean velocity profiles, both of which retain a dependence on the slot height H. As such, incomplete similarity of the wall jet on smooth and transitionally rough surfaces is confirmed by this study. In addition, comparison of the experimental results for the transitionally rough surface with the smooth wall case indicates that the surface roughness modifies the development of the mean velocity profile in both the inner and outer regions, although the effect on the outer region is relatively small and close to the experimental uncertainty.     

Roughness measurement of metallic surfaces based on the laser speckle contrast method

A method of measuring surface roughness of flat lapped, ground and polished metallic surfaces, by the far-field speckle contrast method is presented in this paper. The laser speckle contrast technique depends on the existence of an approximately linear relationship between the speckle contrast and the roughness of the illuminated surface. Initially it was shown that the linear relationship existed up to 0.1 μm Ra (centre-line average) roughness using Helium–Neon light, after which a saturation effect was observed. The effect of varying the incident angle of illumination was investigated with a view to extending the measurement range. The use of high incident angles of illumination has been found to increase the surface roughness range up to 0.4 μm measurement Ra.     

CuAg纳米结构表面共存和Ag表面对甘氨酸的新吸附行为

在异质纳米结构表面发生的新现象是当前研究的热点.最近发现，尽管甘氨酸在纯Ag表面只 能作物理吸附，蒸镀在Cu表面的单层Ag岛却能在Cu的帮助下，出现对甘氨酸作化学吸附的能力，这种现象是溢流效应的一种反映.蒸镀在Ag表面的Cu岛也能帮助附近裸露的Ag表面获得 化学吸附甘氨酸的能力，虽然这里已不是单原子层的银了.结果说明这种溢流现象来源于CuA g在表面的纳米结构共存，而不只是这种共存的某个结构所特有的.但是，由于Cu的表面能大 于Ag，所以即使是在室温下，Cu岛也会逐渐地被一单层Ag原子完全覆盖，从而失去溢 关键词： 溢流 甘氨酸 Cu Ag(111)