利用二维杨-顾算法设计非对称结构衍射光学元件

杨 顾算法是一种设计衍射光学元件的相位恢复方法。在大多数文献中,主要用它来设计一维衍射光学元件和具有旋转对称结构的二维衍射光学元件,故在此称之为一维杨 顾算法。二维杨 顾算法可用来设计任意结构的二维衍射光学元件。在基于非幺正变换光学系统中,用振幅 相位恢复理论建立了二维杨 顾算法的数学模型,给出了迭代算法。利用自编的仿真程序包设计了一个具有非对称结构的衍射相位元件。     

有限口径非周期亚波长衍射聚焦偏转器的严格矢量优化

有限口径非周期亚波长衍射光学器件的亚波长结构特性使得传统标量衍射理论失效,必须借助严格电磁理论进行器件的设计。提出一种循环平面波谱算法(IterativePlaneWaveSpectrumAlgorithm,IPWSA)作为器件优化算法,利用二维时域有限差分方法作为严格电磁计算模式,根据Farn方法对器件面型进行亚波长处理,设计出有限口径非周期具有亚波长结构的衍射聚焦偏转器件,偏转角为24.8°,该器件可与激光器集成构成微型集成光学系统,也可以用在红外量子阱系统中。详细分析了算法原理,设计实例验证了算法的优化效果。     

多层衍射元件的浮雕深度和基底材料的优化分析

在分析单层和多层衍射元件衍射效率的基础上,推导出光学系统中多层衍射元件浮雕深度和基底材料的一般关系式,并对这些变量进行优化,得到阿贝数的值大致在20～80之间,β的合理值在0.25～0.6之间,当2个衍射元件的阿贝数v1＜v2,且差值比较大时,阿贝数小的衍射元件的基底材料选择光学玻璃中的火石玻璃,阿贝数大的衍射元件的基底材料选择光学玻璃中的冕牌玻璃。根据这个方法,设计了3组可实现宽波段高衍射效率的不同材料、不同浮雕深度的组合,使得每组组合中两层衍射元件的衍射效率都在99%以上。     

用于衍射光学元件优化设计的遗传算法及其与模拟退火算法的比较

本文成功地将遗传算法运用于高维衍射位相光学元件的优化设计.并与模拟退火算法进行了比较.结果表明,该算法不仅对于二元,而且对于多元位相光学元件的优化疫计均是十分有效的.而且,它特别适用于利用光电混合处理系统进行优化计算.     

Design of wavelength-selective waveplates using genetic algorithm

Wavelength-selective waveplates, which act either identically or differently for plural wavelengths, are useful for optical systems that handle plural wavelengths. However, they cannot be analytically designed because of the complexity of their structure. Genetic algorithm is one of the methods for solving optimization problems and is used for several kinds of optical design (e.g., design of thin films, diffractive optical elements, and lenses). I considered that it is effective for designing wavelength-selective waveplates also and tried to design them using the genetic algorithm for the first time to the best of my knowledge. As a result, four types of wavelength-selective waveplate for three wavelengths (405, 650, and 780 nm) were successfully designed. These waveplates are useful for Blu-ray Disc/Digital Versatile Disc/Compact Disc compatible optical pickups.     

一种通用的辐射聚焦器设计方法

本文把辐射聚焦器设计当作逆衍射问题求解，在吸收“模拟退火”思想的基础上，提出了一种通用性强、抗局部极值性好的优化算法──Ｉｍｐｒｏｖｅｄ－ＡＬＯＰＥＸ法，并就如何控制优化过程中的温度与步长两参量，进行了详细的讨论，剔除了ＡＬＯＰＥＸ法中存在的一些问题，最后比较了Ｅｒｒｏｒ－Ｒｅｄｕｃｔｉｏｎ法和本方法的设计结果。     

利用汉克尔变换设计高斯光束整形衍射元件的应用研究

衍射光学元件由于可以实现对高斯光束的整形而被重视,其通常的设计方法为G-S算法,由于使用傅里叶变换运算量大、费时长,将快速汉克尔变换应用到这些算法中可以极大地提高运算速度,节省运算时间,为设计复杂的光束整形元件提供了高效、可行的方法。本文利用该种方法设计针对中心波长为775 nm、光束束腰口径为6 cm的激光器,成功设计了一个具有二阶相位的折衍混合光学元件。仅单独这一片元件,既可在距离其35 m处得到一半径为200μm的圆形平顶光斑,均方根误差D0.021。当抽样值取2~15时,在普通PC机上运行时间仅为20.05 s,大大节省了优化设计时间(整个优化设计过程往往需要几十次甚是上百次这种运算)。同时利用离子刻蚀技术加工了该折衍混合元件,并进行了实际测试,结果与设计值基本相符,整形效果较好。这种单片的整形元件不仅整形效果好,还有利于与激光器的集成,简化系统的调节。     

Design and fabrication of Fourier plane diffractive optical elements for high-power fibre-coupling applications

In industrial processes using fibre beam delivery of high peak power laser light, diffractive optical elements are a very useful and flexible tool in maximising the amount of light reaching the work surface. This is due to the ability of diffractive optical elements to accurately couple light into multiple fibres, while conditioning the light in order to maximise the throughput for each fibre. We discuss the design techniques for diffractive optical elements and the application of these techniques to fibre-coupling problems. The flexibility of diffractive optical elements is demonstrated by their application to several fibre-coupling geometries, including a fibre bundle, a linear array of fibres, and a rotationally symmetric fibre connector. The diffraction efficiencies for the elements approach 90% with uniformity errors of less than 5%.     

列阵均匀照明系统的优化设计

 结合理论分析和神光系列装置均匀照明系统的设计和实验经验, 从光的衍射、干涉与光束质量等角度分析了由透镜或衍射光学元件组成的列阵大焦斑均匀照明系统参数与靶 面焦斑强度分布的关系, 提出了列阵系统的优化设计方法。     

A New Fourier Iterative Algorithm for the Design of Phase－only Diffractive Optical Element Used in Laser Beam Shaping

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用于光束整形的衍射光学元件设计的混合算法

提出了一种用于衍射光学元件优化设计的混合遗传迭代爬山算法,该算法将迭代量化傅里叶变换算法融入到遗传算法中,然后在整体遗传算法结束后,对找到的当前最优解再用爬山法进行局部寻优,从而得到最优的衍射光学元件表面相位分布.用该混合方法设计了衍射光学元件,可以将入射的高斯光束整形成方形的均匀光斑.模拟结果表明:该混合算法具有收敛速度快、设计准确度高等优点.相比于其它设计方法,本文提出的方法能较好地改善整形效果,特别适用于光束整形的衍射元件设计.     

多色光大空间带宽积傅立叶变换透镜系统的设计

本文根据傅立叶变换透镜系统的像差要求，通过研究衍射器件的色差特性和初级像差特点，提出了多色光大空间带宽积的傅立叶变换透镜的系统结构。此系统采用无光焦度的衍射器件校正傅立叶变换主镜的球差，使系统得到最大空间带宽积；还采用谐衍射器件的设计方法，使系统可对多种相干光实现光学傅立叶变换。相对传统傅立叶变换系统而言，此衍射系统结构简单，性能好，可望在光学信息处理方面得到广泛的应用。     

Binary diffractive beam splitters with arbitrary diffraction angles

Diffractive optical beam splitters designed with iterative Fourier transform type algorithms can produce only certain diffraction angles given by the spatial frequencies used for the computations, which are multiples of a certain base spatial frequency. We have developed a design algorithm that overcomes this limitation and can be used to compute binary diffractive elements with arbitrary diffraction angles. The simulated and experimentally measured properties of optical elements producing beam arrays in circular arrangements are presented and discussed.     

采用分步迭代算法设计制作衍射光学元件

 结合均匀照明相位器件的设计实例，介绍最新提出的基于迭代框架的优化方法，并应用该方法设计制作了16台阶的衍射光学元件并对其进行了测试，验证了设计原理及方法的正确性，且对加工中可能出现的误差进行了分析和讨论。测试结果验证了采用多台阶相位结构的设计方案能有效提高工艺宽容度。     

一种用于均匀照明的衍射光学元件设计的快速模拟退火法

介绍了一种适用于均匀照明的衍射光学元件设计的自洽迭代和优化混合的快速模拟退火法,它引入Tsallis正则分布以及相应的效用函数思想,可以在接近1%的时间内得到和传统模拟退火法有着相同均方差(MSE)的理想模拟结果.     

DESIGNING A DIFFRACTIVE OPTICAL ELEMENT FOR CONTROLLING THE BEAM PROFILE IN A THREE-DIMENSIONAL SPACE USING THE SIMULATED ANNEALING ALGORITHM

We have designed a spatially quantized diffractive optical element (DOE) for controlling the beam profile in a three-dimensional space with the help of the simulated annealing (SA) algorithm. In this paper, we investigate the annealing schedule and the neighbourhood which are the deterministic parameters of the process that warrant the quality of the SA algorithm. The algorithm is employed to solve the discrete stochastic optimization problem of the design of a DOE. The objective function which constrains the optimization is also studied. The computed results demonstrate that the procedure of the algorithm converges stably to an optimal solution close to the global optimum with an acceptable computing time. The results meet the design requirement well and are applicable.     

一种用于减少相位突变点的衍射光学元件改进设计方法

提出了一种基于数字图像处理技术的用于降低相位突变点的改进型Gerchbery-Saxton(G-S)衍射光学元件设计方法。与普通的G-S衍射光学元件设计算法相比,这种改进型的G-S算法能够使得衍射光学元件的相位分布曲线更加光滑,并且在迭代计算过程中具有更强的收敛能力。利用该种算法获得了由高斯光束变换成空心光束时所需要的衍射光学元件的相位分布,在同样参数条件下,均方根误差为8.31%,优于普通G-S算法的9.46%;并且约有33.2%的像素的相位值得到了改进,从而平滑了衍射光学元件的相位分布曲线,便于实际的微加工。     

Efficient method for evaluation of the diffraction efficiency upper bound of diffractive phase elements

The theoretical diffraction efficiency upper limit of diffractive phase elements (DPE's) with finite apertures is investigated. A successful numerical method of evaluating the efficiency upper bound of DPE's is proposed. The method includes a hybrid optimization procedure that combines a genetic algorithm with the conjugate gradient method. This efficient global optimization technique can also be used to design DPE's. Simulation computations are detailed for rotationally symmetric beam shaping in which a Gaussian profile laser beam is converted into a uniform beam. Numerical results demonstrate that the estimated diffraction efficiency upper bound is consistent with the design results.     

Diffractive optics: Design, realization, and applications

This paper presents methods for designing and recording optimal computer-generated diffractive optical elements. The design method is based on an analytic ray-tracing procedure for minimizing aberrations. The recording involves computer-generated masks and multiple lithographic processes in order to form reflective and transmissive multilevel, surface relief-phase, diffractive elements. As a result, the elements can have high diffraction efficiencies over a broad range of incidence angles. Even generalized diffractive elements that operate with highly uniform diffraction efficiency and polychromatic radiation can be designed and recorded by optimizing the shape and height of the relief gratings. To illustrate the effectiveness of the diffractive optical elements, they have been incorporated into a number of applications, involving visible as well as infra-red radiation. Some that deal with coordinate transformation, beam shaping, and polarization control are briefly reviewed.     

非制冷长波红外热像仪折衍混合双视场光学系统设计

根据衍射光学元件具有大的负向色散特性,将衍射光学元件应用于红外双视场光学系统中,根据傅里叶光学分析衍射光学元件(DOE)的消色差,列表对比折射透镜与衍射光学透镜的特性,并给出变倍比为4∶1可用作非制冷红外热像仪的光学系统的具体设计实例.系统采用切入式变焦方式,在短焦时切入2片透镜实现宽视场,通过引入二元面和非球面提高了成像质量.设计结果表明:在空间频率11 lp/mm处,短焦距40 mm时,各个视场的MTF值均大于0.6;长焦距160 mm时,各个视场的MTF值均大于0.7,宽视场和窄视场都具有较好的成像质量.