Numerical analysis of dielectric lens antennas using a ray-tracing method and HFSS software

In this paper, we use for the first time the ray-tracing method combined with the HFSS software to analyze lens antennas. HFSS is a very popular commercial tool that can provide very accurate results for the simulation of antennas. However, because of limitations on computational resources, it is hard to apply to solving large electromagnetic problems. In this paper, HFSS is used to simulate the fields of the feed part of a lens antenna. The ray tracing method is adopted for the lens part. This treatment makes the combined method feasible for solving large lens antennas. In using the ray-tracing method, cubicspline interpolation is exploited to fit the face of the lens and to solve for the derivatives at each point on the curved surface. Newton's method is applied to find the intercept between the ray and the curved surface. The numerical method proposed in this paper is very suitable for the analysis of dielectric lens antennas with arbitrary feeds and lens shapes. The validity of the idea is demonstrated by comparing the simulation results of this new method with those from using CST (Computer Simulation Technology) software. Very good agreement is achieved.     

用于LED均匀照明的自由曲面菲涅耳TIR透镜光学设计

为了提高透镜的散热能力,设计了一种新型全内反射（TIR）透镜,该透镜的出射面中央为自由曲面菲涅耳面。采用斯涅尔定律和全反射定律分别求解TIR透镜折射部分和反射部分自由曲面的面形。同时,采用一种菲涅耳透镜的普适设计方法将折射部分自由曲面转变成菲涅耳面。通过蒙特卡洛光线追迹模拟自由曲面菲涅耳TIR透镜的照明效果,结果显示:当光源尺寸为2 mm×2 mm时,其远场照度均匀性为82%,光效为96.6%,透镜质量为21.94 g。与未加菲涅耳面的TIR透镜相比,带自由曲面菲涅耳面的TIR透镜在光效仅下降2%,在照度均匀性未变的情况下,透镜质量减少了约20%。这说明对TIR透镜的自由曲面出射面进行菲涅耳化可明显地缩小透镜的体积和质量,缩短光线在透镜内部的光程,因此可有效提高透镜的散热效率和使用寿命,同时保持良好的照明效果。     

旋转轴对称LED均匀照明系统设计方法

基于边缘光学理论,提出了一种应用于LED照明的光学系统设计方法,分别实现基于透镜和反射器的LED均匀照明光学系统,可在一特定距离的目标面上形成均匀圆形光斑。采用基于蒙特卡罗法的光线追迹软件对两种光学系统进行模拟仿真,结果显示,目标面上光斑的均匀度优于85%,系统效率高于90%。     

单个非球面扩束透镜的设计

为设计单个非球面扩束(缩束)透镜,由光线折射定律矢量形式和对非球面折射特性的理论分析,提出了一种设计单个非球面扩束(缩束)透镜的新方法全面学习策略的粒子群算法,并用此方法设计出了线度小于170 mm缩束14.16倍的单个非球面缩束透镜,用光线追迹方法模拟了缩束或扩束过程。模拟结果表明,单个非球面透镜可以起到缩束或者扩束作用,全面学习策略的粒子群算法可用于非球面缩束透镜的设计。单个非球面透镜作为扩束镜使扩束系统结构大大简化,大大提高了出射光斑的均匀性。     

High-frequency analysis of integrated dielectric lens antennas

A high-frequency method for the three-dimensional analysis of integrated dielectric lens antennas is presented. This method consists on improving the physical optics (PO) currents on the lens surface by modifying, via suitable transition functions, the spreading factor of those rays from the source point which arrive at the lens-air interface close to the critical angle of incidence. Invoking the locality principle of the high-frequency phenomena, the method uses the rigorous canonical solution of the semi-infinite dielectric space locally tangent at the lens surface. A uniform asymptotic evaluation of this canonical solution is provided with the introduction of a new transition function for the TM case. The present formulation provides significant correction from the PO currents of an elliptical lens, with a consequent improvement of the radiation pattern prediction, testified by comparisons with results from a full-wave analysis.     

实现大范围均匀照明的LED透镜二次光学设计

提出了一种新的、利于实施计算的实现大范围均匀照明的LED灯具透镜设计方法。基于能量守恒定理和光线折射Snell定理,通过Matlab编程计算出自由曲面透镜坐标点。借助CAD软件和光学模拟软件Tracepro,模拟了自由曲面透镜的具体应用,在光源高为3m,接收面直径为10m的圆形照明区域,得到了均匀度达80%以上的照度分布,该设计可以应用在商场、工厂等室内照明灯具上。     

倒锥透镜型单模光纤端的光学传递特性

倒锥透镜型光纤端由特殊技术加工而成。本文给出了这种光纤端的折射率分布。借助于光纤在球面上的折射公式及光线传输方程,分析了这种新型单模光纤端的光学传递性质。在近轴近似下,给出了这种光纤端的光学传递矩阵。     

Theory of cathode trajectory characterization by canonical mapping transformation

The paraxial lens theory cannot directly be applied to the cathode trajectories inside the gun. This inconvenience makes the interpretation of cathode trajectories difficult since one cannot use the physical concepts familiar in the paraxial lens theory, such as focal length and magnification factor. We have proposed the canonical mapping transformation (CMT) to describe the electron trajectories inside the gun by relating the ray conditions on the cathode surface to those in the crossover plane. The method takes as variables the distance along the surface and the sine of the ray angle with respect to the surface normal to define ray conditions. It has been shown that the CMT can be characterized by a small number of optical parameters. One of the parameters is the 'electron gun focal length', an extension of the image side focal length in the paraxial lens theory. The crossover size of a triode gun can be calculated from the electron gun focal length and the initial transverse energy spread. The calculation predicts the dependence of the crossover size on the grid voltage due to the change in the electron gun focal length. The prediction is compared with the measurement and shows good agreement with it. Since the CMT optical parameters can be calculated from the representative trajectories only and as they predict practically all the necessary source properties of guns, the CMT can be used as a practical tool in the designing of various types of electron guns.     

基于柱透镜光栅的合成图像生成及分辨率损失

根据柱透镜单元光传输原理,提出了一种非均匀宽度视差图条纹及其在合成图像中非均匀排列的方法,该方法可以减少立体图像串扰,增加各个视点接收到的对应视差图的信息量,使观看到的自由立体图像更加清晰。此外,置于LCD屏前的柱透镜光栅条纹方向与屏表面的坐标轴倾斜角度的改变会导致图像在竖直和水平方向分辨率的变化。与光线追迹测量分辨率损失的ASAP软件模拟法不同,本文以解析法分析了光栅条纹倾斜角度对竖直和水平方向分辨率损失的影响,计算结果对柱透镜光栅自由立体显示器的设计有一定的参考性。     

基于LED光源的TIR透镜的优化设计

为提高LED光能利用率,设计了一种自由曲面的全内反射(TIR)透镜。根据LED的光能分布特点,通过控制光线路径得到TIR透镜折射面和反射面轮廓曲线上的离散点,利用插值得到样条曲线,再经旋转360°得到TIR透镜的模型。利用Tracepro软件对经TIR透镜的光线进行追迹,根据光能利用率要求优化透镜结构,得到在保持透镜小尺寸的同时,光能利用率为95.26%,光束的发散角控制在±15°以内。     

非球面内表面调制的自由曲面配光透镜设计方法

传统自由曲面LED配光透镜由于在自由曲面求解时存在误差,往往导致最终配光效果不理想。为了进一步提高配光效果,提出基于非球面内表面调制的自由曲面配光透镜设计方法,采用非球面内表面对自由曲面的求解误差进行补偿,有效地减小了自由曲面的误差对配光效果的影响。通过对自由曲面求解误差进行定量计算,建立用于补偿误差的非球面内表面设计方法,形成了基于非球面内表面调制的自由曲面配光透镜的完整的设计思路。将这一方法应用于矩形照明区域的LED路灯透镜设计之中,相对于传统自由曲面配光透镜,照度均匀度由0.66提高到0.73,能量利用率从47.3%提高到63.2%。     

New calculations for coupling laser diode to multimode fiber

A simple and useful method is presented for calculating characteristics of a laser diode to a multimode fiber coupling. Attenuation of higher order modes in multimode fiber is introduced into ray tracing. Maximum coupling efficiencies and misalignment tolerances of optical circuit components are computed for utilization of a relatively large spherical lens and combination of two relatively large spherical lenses. It is clarified that attenuation of higher order modes strongly affects both maximum coupling efficiency and misalignment tolerances. Agreement between theoretical and experimental coupling characteristics is greatly improved compared with the case for conventional ray tracing.     

毫米波新月形柱面透镜天线设计

设计了一个毫米波均匀介质新月形柱面透镜天线。考虑到透镜天线设计中遇到的计算过程复杂、工作量大的问题,提出采用射线追踪法分析毫米波透镜天线,通过MATLAB编程仿真得到满意的效果。该结果与其他仿真结果基本吻合,但是具有省时和节省计算机存储空间等优点,可作为毫米波透镜天线设计的优选方案。     

光场相机建模与畸变校正改进方法

光场相机作为一种新型的成像系统,可以直接从一次曝光的图像中得到三维信息。为了能够更充分有效地利用光场数据包含的角度和位置信息,完成更加精准的场景深度计算,从而提升光场相机的三维重建的精度,需要实现精确的几何建模,并精确标定其模型参数。该方法从薄透镜模型和小孔成像模型出发,将主透镜建模为薄透镜模型,将微透镜建模为小孔成像模型,结合光场相机双平面模型,将每个提取到的特征点与其在三维空间中的射线建立联系,详细解释了内参矩阵中每个参数的物理意义,以及标定过程中初值确定的过程,并在镜头径向畸变模型的基础上进一步应用了相机镜头的切向畸变模型以及基于射线重投影误差的非线性优化方法,改进了光场相机的标定方法。实验显示,该方法的RMS射线重投影误差为0.332 mm,与经典的Dansereau标定方法相比,进行非线性优化后得到的射线重投影误差精度提升了8%。该方法详细分析的场景点与特定像素索引的推导过程对光场相机的标定具有重要的研究意义,为光场相机光学模型的建立与初始化标定奠定了基础。     

局域空心光束尺寸变换的模拟及实验

不同尺寸的局域空心光束可囚禁不同尺度的微粒,在生命科学和纳米科技中具有重要的意义.提出了一种利用普通球面透镜望远系统来变换局域空心光束尺寸的新方法.利用几何光学方法进行了分析,采用ZEMAX光学设计软件实现光线追迹进行模拟.实验中拍摄并测量了经望远系统变换前后的局域空心光束的尺寸.结果表明,局域空心光束尺寸的变换比等于...     

单个椭球面扩束透镜的设计研究

为了设计单个椭球面缩束(扩束)透镜,采用全面学习策略的粒子群算法作为设计方法,依据光线折射定律矢量形式所表征的椭球面折射特性进行了理论分析,得到了用全面学习策略的粒子群优化算法设计单个椭球面缩束(扩束)透镜的适应度数据公式,设计出了线度小于170mm缩束14.16倍的单个椭球面缩束透镜,并用光线追迹方法模拟了缩束或扩束过程。结果表明,单个椭球面透镜可以起到缩束或者扩束作用,全面学习策略的粒子群算法可用于椭球面缩束透镜的设计。这一结果对于简化扩(缩)束系统结构、设计出适应于不同要求的单个扩(缩)束透镜是有帮助的。     

Comparison of Diffraction Fields of Lens by Two Calculation Formulas

Diffraction fields in the focal space of some lens is investigated by using ray tracing and Stratton-Chu formulas. Two formulas are used. One is surface integration formula, and for another a line integration is added. Comparison of two calculation results is given. It is shown that for hyperbolic lens two calculations results are same and for extended hemi-ellipsoidal lens there are a lilt difference between them.     

空间红外探测系统外部杂散光分析与抑制

为降低视场外太阳辐射对空间红外探测系统的影响,对系统的遮光罩和挡光环进行了设计与优化。在ZEMAX软件下,建立了光机结构分析模型,采用非序列模式下的光线追迹方法,计算了视场外太阳辐射经镜筒表面及透镜表面的多次散射或反射到达探测器表面的杂散光辐照度。根据计算结果对遮光罩和挡光环的参数进行了优化,使得杂散光抑制水平满足系统要求。     

扫描电子束曝光机复合物镜的研究与设计

在综合研究已有的各种复合物镜(如移动物镜、变轴物镜和摆动物镜等)的基础上,本文对复合物镜的一般理论进行了探讨,推导了普遍化计算公式,并提出新的复合物镜(弯曲物镜)系统。采用解析函数近似表示系统场分布,对弯曲物镜系统象差进行了理论分析,并设计出一个实际系统。数值计算结果给出该系统在55mm2扫描场内,束孔径角5mrad和能散2.5eV下,最大彗差0.005m,横向色差0.001m。