Large-area straight,regular periodic surface structures produced on fused silica by the interference of two femtosecond laser beams through cylindrical lens

Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtosecond lasers was used to produce large-area straight LIPSSs on fused silica using cylindrical lenses.Compared with those produced us-ing a single circular or cylindrical lens,the LIPSSs produced by TBI are much straighter and more regular.Depending on the laser fluence and scanning velocity,LIPSSs with grating-like or spaced LIPSSs are produced on the fused silica sur-face.Their structural colors are blue,green,and red,and only green and red,respectively.Grating-like LIPSS patterns oriented in different directions are obtained and exhibit bright and vivid colors,indicating potential applications in surface coloring and anti-counterfeiting logos.

Measuring Topological Charges of Optical Vortices with Multi-Singularity Using a Cylindrical Lens

We present a simple method to measure the topological charges of optical vortices with multiple singularities. Using a cylindrical lens, a vortex beam can decay into a light field distribution with multiple separated dark holes, whose number just equals the topological charge of the input beam. This conclusion is then verified via experiments and numerical simulations of the propagation of vortex beams with multiple singulaxities. This method is also reliable to measure the topological charges of broadband vortex beams with different distributions of singularities, which does not resort to multiple beam interferometrie experiments.

OPTICAL OPTIMIZATION FOR LIQUID CRYSTAL TEST BY LASER-CCD SYSTEM

For the narrowband of liner charge-coupled device （CCD） receiver and the imaging rule that cylindrical lens system can compress round facula into narrow and long one, the system is simplified and light force can concentrate on a strip facula, Considered the effective CCD length and selection of lens parameters, the system can be optimized. Correspondingly to the CCD pixels, the ray is composed of much angle information. By widening the parallel ray or increasing the lens aperture, luminous flux can be ensured when oblique incidence. Meanwhile, the effective working range can also be improved. Based on the experimental data, cylindrical system could be applied in accurate angle measurement. It has been proved feasible that the cylindrical system can be used in anchor behavior study for liquid crystal （LC） case. The low-power He-Ne laser cylindrical system can carry out the previous effect in high power laser spherical system.

Measurement and verification of concentration-dependent diffusion coefficient:Ray tracing imagery of diffusion process

Ray tracing method is used to study the propagation of collimated beams in a liquid-core cylindrical lens(LCL),which has dual functions of diffusion cell and image formation.The diffusion images on the focal plane of the used LCL are simulated by establishing and solving both linear and nonlinear ray equations,the calculated results indicate that the complex imaging results of LCL in inhomogeneous media can be treated by the law of ray propagation in homogeneous media under the condition of small refractive index gradient of diffusion solution.Guided by the calculation conditions,the diffusion process of triethylene glycol aqueous solution is experimentally studied at room temperature by using the LCL in this paper.The spatial and temporal concentration profile Ce(z,t)of diffusion solution is obtained by analyzing diffusion image appearing on the focal plane of the LCL;Then,the concentration-dependent diffusion coefficient is assumed to be a polynomial D(C)=D0×(1+α1C+α2C2+α3C3+…).The finite difference method is used to solve the Fick diffusion equation for calculating numerically the concentration profiles Cn(z,t).The D(C)of triethylene glycol aqueous solution is obtained by comparing the Cn(z,t)with Ce(z,t).Finally,the obtained polynomial D(C)is used to calculate the refractive index profiles nn(z,t)s of diffusion solution in the used LCL.Based on the ray propagation law in inhomogeneous media and the calculated n(z,t),the ray tracing method is used again to simulate the dynamic images of the whole experimental diffusion process to varify the correctness of the calculated D(C).The method presented in this work opens up a new way for both measuring and verifying the concentration-dependent liquid diffusion coefficients.

Study on the adaptability of augmented reality smartglasses for astigmatism based on holographic waveguide grating

Background Augmen ted reality(AR)smartglasses are considered as the next generation of smart devices to replace mobile phones,and are widely concerned.But at present,AR smartglasses are usually designed according to the human normal eyes.In order to experience AR smartglasses perfectly,abnormal eye users must first wear diopters.Methods For people with astigmatism to use AR smartglasses without wearing a diopter lens,a cylindrical lens waveguide grating is designed in this study based on the principle of holographic waveguide grating.First,a cylindrical lens waveguide substrate is constructed for external light deflection to satisfy the users'normal viewing of the real world.Further,a variable period grating structure is established based on the cylindrical lens waveguide substrate to normally emit the light from the virtual world in the optical machine to the human eyes.Finally,the structural parameters of grating are optimized to improve the diffraction efficiency.Results The results show that the structure of cylindrical lens waveguide grating allows people with astigmatism to wear AR smartglasses directly.The total light utilization rate reaches 90%with excellent imaging uniformity.The brightness difference is less than 0.92%and the vertical field of view is 10°.Conclusions This research serves as a guide for AR product designs for people with long/short sightedness and promotes the development of such products.

重型刮板输送机柱面摩擦限矩器过载保护特性研究

为减少刮板输送机发生卡链和断链等故障,研究了一种柱面摩擦限矩器,该限矩器具有结构紧凑,精准打滑、快速恢复及可靠性高等优点。因此,为探究柱面摩擦限矩器的过载保护性能,运用AMESim建立刮板输送机整机模型,利用Matlab/Simulink搭建限矩器打滑控制模型进行联合仿真,研究了冲击工况和卡链工况柱面摩擦限矩器的过载保护特性,分析了限矩器不同安装位置对刮板输送机的过载保护效果。结果表明,在冲击和卡链工况下由于限矩器发生摩擦打滑,有限矩器保护的刮板输送机整机受力较为平稳未发生突变性增长,限矩器隔离尖峰载荷作用显著。当限矩器布置于减速器中间时对刮板输送机及其驱动系统的保护效果最优,柱面摩擦限矩器的研究为提高刮板输送机的可靠性和使用寿命提供理论指导和技术支持。

周边离焦设计框架眼镜在近视防控中的进展

近视在世界各地越来越普遍,发病人群也逐渐扩大。多种治疗方法已经被用于近视防控,包括光学、药物、环境或行为等,但结果各不相同,而且缺乏标准化。周边离焦技术目前已有多项试验证明其对近视控制有一定的作用。基于这一技术,在中国的医疗和视光机构常见到多区正向光学离焦技术(DIMS)、高非球面微透镜技术(HAL)和同心圆带微柱镜技术(CARE)三种周边离焦设计的框架眼镜镜片。这些镜片在提供了中央区清晰视觉的同时,在周边提供了一定量的近视性离焦来控制近视的进展。文章目的是关注以上三种周边离焦设计镜片的设计原理和近视防控效果,并评价其在临床实践中的有效性。

柱面摩擦限矩器接触特性及打滑转矩影响因素研究

为了促进柱面摩擦限矩器在刮板输送机驱动系统上的应用,应用ANSYS有限元软件建立了数值模拟模型,仿真分析了给定油腔压力作用下柱面摩擦副的接触应力分布情况,通过公式得到了打滑转矩与油腔压力的关系,探讨了油腔长度、油腔厚度、油腔内径以及接触间隙对最大接触应力与打滑转矩的影响,并通过正交试验设计,得出了各因素对最大接触应力与打滑转矩的影响显著性排序。结果表明:通过数值模拟与正交试验设计相结合的方法,获得了柱面摩擦限矩器结构参数对最大接触应力与打滑转矩的影响,为柱面摩擦限矩器的结构设计及打滑转矩预测提供了理论依据。

Experimental study of a micro-scale solar organic Rankine cycle system based on compound cylindrical Fresnel lens solar concentrator

In the present study, a micro-scale solar organic Rankine cycle power generation system was developed. The system comprises of a solar collection system based on compound cylindrical Fresnel lens concentrator and an organic Rankine cycle power generation system integrated with a scroll expander. YD320 and R245 fa were used as the heat transfer fluid and the working fluid, respectively. The effects of the evaporation pressure, the degree of superheat, and the mass flow rate of the working fluid were analyzed to evaluate the solar collection efficiency, the electric power output, the thermal efficiency and exergy efficiency of the system. The results illustrate that both the increasing evaporation pressure and decreasing superheat degree have positive impacts on solar collection efficiency. The electric power increases as the evaporation pressure increases, while the thermal efficiency and the exergy efficiency decrease. However, the system overall efficiency decreases slowly due to the increase of solar collection efficiency. The electric power increases with the increment of the working fluid mass flow rate. The increasing mass flow rate has no visible impact on the thermal and exergy efficiencies of organic Rankine cycle subsystem, whereas a slightly increase of the thermal and exergy efficiencies of the integrated system. The electric power decreases with the increase of the superheat degree, whereas the thermal and the exergy efficiencies of the system increase. The system works more suitably with a higher degree of superheat for the small mass flow rate condition.

基于ZEMAX的板条激光器光束准直系统的设计

在ZEAMX软件的非序列模式下利用几何光路的原理,模拟并仿真了一个可压缩1064nm半导体泵浦板条激光器激光光束的准直系统。此系统由两个相互垂直的椭圆柱面透镜组成。30°和15°分别为半导体激光器的快慢轴初始发散角,经过激光准直系统后,板条激光器在快慢轴方向发散角分别为4.4mrad和3.6mrad,达到了设计要求。

基于CATIA的渐开线非标圆柱齿轮副全参数化精确建模方法研究

基于CATIA软件,对渐开线非标准圆柱齿轮副进行全参数化精确建模的方法进行了研究。所述的非标准圆柱齿轮主要是指齿轮参数的非标准化而非结构上的非标准,重点探讨了非标圆柱斜齿轮建模参数的选取与建立,部分参数需要通过齿轮副或配对齿轮的参数来进行定义,如齿根高、变位等。基于精准参数建模需要,将齿厚、齿顶、齿根等公差纳入相应的建模方程或公式,以实现自动生成精准数模,可以直接用于进一步的功能、可靠性仿真以及有限元设计分析和优化,并且数模的变更或重新设计仅需修改相关的参数就能实现,大大提高了齿轮数模设计效率。

新型柱面摩擦限矩器摩擦副热力耦合特性研究

针对煤矿综采工作面刮板输送机过载保护性能差、可靠性低及寿命短等问题,设计了一种新型高功率密度柱面摩擦限矩器。为了研究打滑过程柱面摩擦副温度场和应力场的变化规律,利用ABAQUS软件建立了柱面摩擦副热力耦合模型,采用直接耦合法分析了不同载荷多种工况条件下摩擦副铜套与衬套的温度场及应力场变化规律。结果表明:在连续打滑工况下,摩擦副铜套与衬套的温度与应力随打滑时间不断增大,且在铜套接触面边缘出现最大应力集中而衬套应力出现交替变化现象,而打滑-同步工况下,随着打滑停止,摩擦副应力温度逐渐降低,在2种工况下,摩擦副温度都随着作用载荷的增大而增大。本研究可为柱面摩擦限矩器的优化设计及疲劳寿命预测提供理论依据。

基于滑动率最小的渐开线圆柱齿轮传动优化设计

针对渐开线圆柱齿轮传动的设计 ,以一对齿轮副啮合的使用寿命最长为优化设计目标 ,通过调整齿轮的变位系数使齿轮传动的最大滑动率为最小以提高其传动寿命 ,并在此基础上设法使两齿轮最大滑动率相近来使其寿命达到基本一致。探讨了数学模型的建立、算法确定、计算机程序的编制 。

具有不完全概率信息的圆柱齿轮传动的可靠性灵敏度设计

应用随机摄动技术和四阶矩技术,将可靠性设计理论与灵敏度分析方法相结合,建立了圆柱齿轮传动的可靠性灵敏度设计模型,提出了基于四阶矩方法的可靠性灵敏度设计的计算方法,讨论了具有不完全概率信息的圆柱齿轮传动的可靠性灵敏度设计问题,探讨了圆柱齿轮传动的可靠性随设计参数改变的数学评价方法,给出了可靠性灵敏度的变化规律,研究了设计参数的改变对圆柱齿轮传动的可靠性的影响,并且获得了理想的数值设计结果。为圆柱齿轮传动的可靠性设计提供了理论依据。

衍射微柱透镜焦深和焦移特性的矢量分析

当衍射光学元件的特征尺寸可以与照射光波长比拟时 ,必须考虑光波矢量衍射特性。利用矢量分析方法———二维时域有限差分法 (FDTD)对有限口径衍射微柱透镜的焦深和焦移特性进行严格矢量分析 ,与传统标量分析方法的结果进行了详细比较。分析给出TE波垂直入射情况下衍射微柱透镜焦深和焦移与透镜F数的关系 ,结果表明 ,微柱透镜的焦移量要大于标量分析结果 ,而二者得出的焦深量基本一致 ,这些结论对衍射微透镜的设计和实际应用有一定指导意义。同时分析了透镜面型量化对焦深和焦移的影响 ,讨论了矢量分析方法的数值色散。

用于半导体激光器的角倍率相关圆柱面镜系统

利用互相垂直的两组圆柱面镜把半导体激光器的条形窗口成像为矩形．再用球面准直物镜组把此象“准直”到“无限远”．该系统把激光器发出的发散光束压缩到在±０．００２５弧度内出射光．

LD与柱状楔形透镜光纤的耦合特性研究

半导体激光器与光纤的耦合系统的优化设计,可减小耦合损耗,有利于半导体激光器的使用和发展。文章分析柱状楔形透镜光纤与半导体激光器的耦合损耗,运用矩阵光学的ABCD定律建立了柱状楔形透镜光纤与半导体激光器耦合的模型,对激光耦合进入光纤进行计算;通过仿真计算,研究柱状楔形透镜光纤的结构参数对耦合效率的影响与纵、横向位置偏移容忍度。结果表明:柱状楔形透镜光纤各项结构参数中,锥端尺寸与柱面半径对耦合效率的影响较大。锥端尺寸与柱面半径与耦合效率呈反比,在设计的耦合系统中,容忍范围为1.2μm;纵横向偏差存在时,x方向容忍度最低为0.71μm,而y方向的容忍度是x方向的3倍多;在进行柱状楔形透镜光纤耦合实验时要着重减少x方向误差。

滚子歪斜对滚子副润滑性能的影响

为研究圆柱滚子副中的滚子歪斜效应,建立滚子的竖直歪斜和水平歪斜2种弹流润滑模型。求得滚子竖直歪斜时等温条件下有限长线接触润滑问题的完全数值解,分析滚子竖直歪斜角和滚子端部圆角半径对滚子副润滑性能的影响,并将竖直歪斜滚子副润滑的理论结果与试验结果进行比较;利用坐标变换法求得滚子水平歪斜条件下的弹流数值解,分析滚子水平歪斜角对膜厚和压力的影响,并给出了相应的试验结果。结果表明,滚子的竖直歪斜极易引起滚子偏磨,但通过滚子端部修形可缓解油膜压力及厚度沿接触线长度分布不均的程度;滚子一定范围内水平歪斜会导致接触区油膜厚度和压力变化,尤其油膜出口颈缩和第二压力峰变化明显;与滚子水平歪斜相比,滚子的竖直歪斜对润滑更为不利。

平地机回转驱动中圆柱蜗杆副的接触特性分析及实验

针对某平地机回转驱动中圆柱蜗杆传动副的实际啮合效果不理想、接触斑点分布不合理等问题,建立传动副数学模型,研究其啮合特性;建立精确的三维实体模型,用接触有限元法分析了传动副的接触特性,并通过数值实例与样件试验进行了验证。结果表明:选取合适的变位系数可以有效避免根切;对蜗轮滚刀进行合理的增径处理、对传动副进行修形、对蜗杆齿根和蜗轮齿根进行适当的倒圆处理,可降低齿面最大应力;传动副接触斑点检测结果与接触有限元模拟分析结果一致,证明了分析方法的正确性;改进后的蜗杆减速器样机传动效率在38%~43%之间,正转时传动效率略高于反转时传动效率。

柱形棒铣刀铣削锥形螺杆的切削形面产生机理

为了采用柱形棒铣刀实现几何形状较复杂部件螺杆挤出副的高精度铣削加工,根据刀具与工件的空间几何关系,利用柱形刀具截面与工件的实际切削点建立数学模型.经过理论分析推导出在开槽和精加工时由柱形棒铣刀所铣削的实际螺旋形面,说明了其为近似倒锥形而非圆柱形,进而提出了由反求计算校正铣刀摆角的方法,并通过实际试切实验验证了理论分析的正确性.该方法可用于实际切削加工前的计算,以正确确定刀具摆角,有效提高锥形螺杆曲面的加工精度和效率.