微透镜列阵衍射效应所致的串扰

本文分析了微透镜列阵衍射效应的影响因素,推导出了微透镜焦平面上光强分布的解析表达式,对菲涅尔数评价衍射效应的物理含义给予了合理的解释.并利用ZEMAX软件对微透镜列阵进行仿真,基于惠更斯子波直接积分的算法计算得到了微透镜列阵焦平面上的光场强度分布.通过比较不同条件下所得到的计算结果,验证了以菲涅尔数作为微透镜列阵衍射效应评价依据的的合理性,同时验证了以菲涅尔数判断焦斑间串扰的可行性.     

菲涅尔型阵列光纤准直器的研究

菲涅尔透镜列阵，具有易阵列化的优点，设计中心波长相同的透镜列阵和中心波长不同的透镜列阵，并对由此列阵构成的准直器的光束耦合特征进行分析和计算，与通用的准直器的相关参数进行比较，表明菲涅尔透镜列阵在光束准直耦合中具有较高的耦合效率，可以用于制作阵列光纤准直器。     

可用作分光元件的二元菲涅耳透镜

根据菲涅耳衍射理论,采用微光学元件制作技术,通过三次套刻制作出八位相台阶的二元离轴菲涅耳透镜。这种微型光学元件同时具有色散分光和聚焦功能,用来作为分光元件时,具有较高的光谱分辨本领和衍射效率。实验测出其衍射效率大于68%。     

一种新颖的超大点阵分束实现方法

首次提出了一种实现超大卢、阵光束分束的新方法，它是利用位相迭加原理和ＶＬＳＩ技术将光栅分束器和位相型菲涅耳微透镜列阵集成为一体，构成了一种新型的光束分束列阵器件—一菲涅耳计算机源生全息分来器（ＣＧＦＢＳ），以实现１２８×１２８，甚至更高卢、阵数的光点分束。     

空间用平板形菲涅耳透镜的设计和光学效率研究

研究平板形菲涅耳太阳聚光透镜的光学问题,给出了线聚焦和点聚焦透镜的设计方法,讨论了设计参数对透镜光学效率的影响,为这类透镜的最优设计提供理论依据。     

衍射微透镜列阵掩模制作软件的设计

研究了衍射微透镜列阵的设计方法及ＣＩＦ格式掩模数据的数据结构与生成方法,设计了一套产用软件,采用图形切割、跟踪计算等方法,解决了生成子孔径为矩形、六 方形及圆环扇形的衍射微透镜列阵掩模的问题,满足了实际系统对衍射微透镜列阵子孔径形状的各种需求。     

衍射微透镜列阵质量评价方法研究

根据实际工程需要 ,对用于萨克 -哈特曼波前传感器的二元衍射微透镜列阵衍射效率的评价方法进行了研究。导出了制作误差与衍射效率的关系式 ,研究了由测得的制作误差评估衍射效率的方法 ,并建立了一套测量系统。     

带凹槽平板型声透镜聚焦性能的理论分析与数值模拟

基于相位补偿和惠更斯-菲涅尔原理,利用理论分析和数值模拟的方法,研究了一种带凹槽的平板型声透镜,讨论了凹槽个数、声透镜材料等参数对声透镜聚焦性能的影响。结果表明:优化后的菲涅尔声透镜聚声效率理论上可达40%,放大倍数约为7倍,是一种较为高效、成本低廉的新型声透镜。     

二元位相匹配衍射透镜的研究与应用

针对大数值孔径衍射透镜制作难、衍射效率低的问题，探讨了用位相匹配原理对元件结构参数优化设计的方法，研制出８台阶二元衍射位相匹配透镜列阵，达到了预期的效果。采用该方法设计的大数值孔径红外锗透镜和为光聚能器，应用在提高红外探测器性能的实验中。     

微透镜列阵与红外探测器列阵集成芯片的研究

在分析微透镜列阵光聚能原理的基础上,针对背照式256290铂硅红外焦平面探测器列阵 的结构参数,设计了衍射微透镜列阵,使入射光通过硅基底聚焦至探测器的各个光敏面上, 提高光能利用率从而增强探测能力。实验获得了微透镜列阵与红外焦平面集成芯片,并在热成像中取得了良好的结果。     

高效非成像聚光光学系统设计与性能分析

针对菲涅尔透镜存在实际光学效率偏低的问题,本文设计了一种由非球面透镜和棒锥镜组成的高效非成像聚光光学系统。在光学设计软件Zemax的序列模式下对非球面透镜进行了优化设计,通过最大程度地减小球差,像面光斑的几何半径从42 mm降到了1.7 mm。基于此,在Zemax的非序列模式下,完成了非球面透镜和棒锥镜的建模和优化,通过蒙特卡罗光线追迹分析实现了光学效率为87%、接收角为0.9°的非成像聚光光学系统。最后,基于非球面透镜阵列和棒锥镜样品,实现了高倍聚光型光伏模组的封装与测试。测试结果表明,该模组的光电转换效率达30.03%,与菲涅尔透镜构成的高倍聚光型光伏模组相比有显著提升。     

Finite element analysis of multilevel acoustic Fresnel lenses

Fresnel lenses have recently emerged as viable alternatives to conventional spherical lenses for focusing ultrasonic waves in acoustic microscopy systems. Although these lenses are relatively straightforward to manufacture, their bulk represents a major handicap. A remedy to this problem is to use multilevel acoustic Fresnel lenses. Multilevel lenses are surface relief structures that can be fabricated very precisely using existing VLSI semiconductor technology. However, accurate tools for designing lenses to achieve the desired efficiency and power specifications are not available. This paper presents a finite element study of multilevel acoustic Fresnel lenses. Results showing ultrasonic wave propagation through such surface relief structures together with the resulting diffraction profiles are presented. The high efficiency and focusing power of these lenses are also demonstrated. Simulation results together with a discussion on various multilevel lens design issues are presented. These results confirm the advantages of such lenses, and suggest that the finite element model can serve as a valuable tool for designing, simulating, and studying lens profiles prior to their fabrication     

All-optical switchable holographic Fresnel lens based on azo-dye-doped polymer-dispersed liquid crystals

Fabrication of an all-optical switchable holographic liquid crystal (LC) Fresnel lens based on azo-dye-doped polymer-dispersed LCs is reported using a Michelson interferometer. It is found that, upon circularly polarized photoirradiation, the diffraction efficiency of the fabricated Fresnel lens was increased significantly in a reversible manner. We believe this is due to the anisotropy induced by reorientation of the LC molecules coupled with azo-dye molecule orientation due to trans-cis-trans photoisomerization, which modulates the refractive index of the LC-rich regions. We also studied the effect of azo dye on the polarization dependency of the fabricated lens.     

Collimating cylindrical diffractive lenses: rigorous electromagnetic analysis and scalar approximation

Practical collimating diffractive cylindrical lenses of 2, 4, 8, and 16 discrete levels are analyzed with a sequential application of the two-region formulation of the rigorous electromagnetic boundary-element method (BEM). A Gaussian beam of TE or TM polarization is incident upon the finite-thickness lens. F/4, F/2, and F/1.4 lenses are analyzed and near-field electric-field patterns are presented. The near-field wave-front quality is quantified by its mean-square deviation from a planar wave front. This deviation is found to be less than 0.05 free-space wavelengths. The far-field intensity patterns are determined and compared with the ones predicted by the approximate Fraunhofer scalar diffraction analysis. The diffraction efficiencies determined with the rigorous BEM are found to be generally lower than those obtained with the scalar approximation. For comparison, the performance characteristics of the corresponding continuous Fresnel (continuous profile within a zone but discontinuous at zone boundaries) and continuous refractive lenses are determined by the use of both the BEM and the scalar approximation. The diffraction efficiency of the continuous Fresnel lens is found to be similar to that of the 16-level diffractive lens but less than that of the continuous refractive lens. It is shown that the validity of the scalar approximation deteriorates as the lens f-number decreases.     

High-efficiency diffractive waveguide lenses by parametric optimization

The first-order diffraction efficiency of a waveguide diffraction grating is maximized, for a wide range of grating periods, by optimization of the effective-index modulation profile. Three different values of effective-index modulation in the range of 0.02-0.11 are considered. The analysis is performed with the thin-grating-decomposition method. The results are verified by electromagnetic grating theory and applied to the construction of diffractive waveguide lenses with an improved overall efficiency. In the neighborhood of the optical axis, the optimized lens structure is a close approximation of a gradient-thickness Fresnel lens. Significant deviations from this shape appear when the local grating period reduces below ~ 15-25λ, where ~ is the wavelength of the guided mode. Near the edges of a high-numerical-aperture lens, where the local period is ~ 3-6λ, an approximate Bragg grating structure is obtained.