Rigorous electromagnetic design of finite-aperture diffractive optical elements by use of an iterative optimization algorithm

We propose a rigorous electromagnetic design of two-dimensional and finite-aperture diffractive optical elements (DOEs) that employs an effective iterative optimization algorithm in conjunction with a rigorous electromagnetic computational model: the finite-difference time-domain method. The iterative optimization process, the finite-difference time-domain method, and the angular spectrum propagation method are discussed in detail. Without any approximation based on the scalar theory, the algorithm can produce rigorous design results, both numerical and graphical, with fast convergence, reasonable computational cost, and good design quality. Using our iterative algorithm, we designed a diffractive cylindrical lens and a 1-to-2-beam fanner for normal-incidence TE-mode illumination, thus showing that the optimization algorithm is valid and competent for rigorously designing diffractive optical elements. Concerning the problem of fabrication, we also evaluated the performance of the DOE when the DOE profile is discrete.     

Diffractive-refractive correction units for plastic compact zoom lenses

A method of designing a plastic zoom lens with a diffractive-refractive hybrid corrector, comprising one diffractive lens and one refractive lens, is described. The efficiency of this method is demonstrated by designing a compact zoom lens for a mobile phone. This zoom design, incorporating lenses made only of two commercial optical plastics (polymethylmethacrylate and polycarbonate), provides high optical performance.     

Design of code division multiple access filters based on sampled fiber Bragg grating by using global optimization algorithms

In this article, we focus on the design of code division multiple access filters (used in data transmission) composed of a particular optical fiber called sampled fiber Bragg grating (SFBG). More precisely, we consider an inverse problem that consists in determining the effective refractive index profile of an SFBG that produces a given reflected spectrum. In order to solve this problem, we use an original multi-layers semi-deterministic global optimization method based on the search of suitable initial conditions for a given optimization algorithm. The results obtained with our optimization algorithms are compared, in term of complexity and final design, with those given by an hybrid genetic algorithm (the method generally considered in the literature for designing SFBGs).     

梯度反射率镜的设计及镀制

针对所设计的单横模Nd：YAG激光器谐振腔对梯度反射率镜的设计要求，以及遮蔽挡板是实现梯度反射率镜的重要内容，论文建立了精确设计遮蔽挡板的数学模型，提出了设计遮蔽挡板的算法，编程计算出具体的遮蔽挡板的孔径尺寸及安放位置，并分析模拟了遮蔽挡板的位置误差对反射率分布的影响。最后，根据遮蔽档板的设计与模拟分析，实际镀制出与设计目标相吻合的梯度反射率镜。     

Synthesis of symmetric and asymmetric planar optical waveguides

A novel and accurate refractive index profile synthesis method for planar optical waveguides is presented and demonstrated using the transmitted near-electric-field-data. This method is based on the inverse transmission-line (TL) technique. From Maxwell's equations, a TL equivalent circuit (electric T-circuit) for the refractive index profile of a planar optical waveguide is derived. The authors demonstrate how to use this model to carry out the inverse problem and synthesise the exact refractive index profile numerically from near-field-data. The TL method can reconstruct arbitrary refractive index profiles for planar optical waveguides that support singlemode or multi- modes. The cases of both symmetric and asymmetric arbitrary refractive index profile planar waveguides are discussed. The accuracy of the reconstructed waveguides is examined numerically.     

Measurement method for profiling the residual stress and the strain-optic coefficient of an optical fiber

A method, believed novel, is demonstrated for determining the strain-optic coefficient profile as well as the residual-stress profile of an optical fiber by use of a modified polariscope combined with a fiber-elongation apparatus. Measurement results of the residual-stress and the strain-optic coefficient profiles for Ge-doped and Er-Ge-Al-doped optical fibers are demonstrated with this method.     

Dispersive mirror in AlGaAs designed by inverse spectral theory

We introduce a new mathematical method, based on the inverse spectral theory of Gel'fand and Levitan, of designing dispersive coatings for use in femtosecond lasers. We fabricated an example in AlGaAs by metal-organic chemical-vapor deposition. The mirror has a high value of group delay dispersion over a bandwidth of 10 nm, reaching an extreme of -1200 fs(2) at the center (805 nm) and falling to -800 fs(2) at the edge of this range. In the same band the reflectivity remains over 95%. We created the design by identifying parameters in the spectral domain, numerically optimizing these parameters, and solving the resulting inverse problem to recover the refractive-index profile. Because we performed the optimization in the spectral domain, we needed only four parameters to obtain a good result. Numerical analysis shows that the excess optical delay at the red end of the stop band can be achieved by use of a mild optical resonance, with the optical field approximately twice the magnitude of that at the blue end.     

Numerical analysis of modal dispersion in graded-index plastic optical fibers

Modal dispersion properties of a fabricated plastic optical fiber are numerically calculated through a finite-element method. The modal index, group delay, impulse response, and output pulse shape are compared with those for the power-law profile plastic optical fiber; the influence of index profile deviations from the power-law profile is described. It is shown that index profile fluctuations in the actual index profile strongly affect the group delays, even though they are relatively small. On the other hand, they have little effect on the modal indices.     

Designing an optical disk lens without analytical definition of aspheric surfaces

We have developed a new method to design aspheric lenses. The conventional technique is usually based on analytic definition of optical surfaces; in the new method discretely defined aspheres are used, and the final design is attained point by point with an iterative algorithm. Simulation results are compared with results obtained with conventional optical design software to prove that this new method is more effective and reliable for designing aspheric lenses, especially when the aspheric order is high.     

半光斑成像式多功能激光瞄准测头的研究

运用半光斑成像原理设计了一种用于三坐标测量机的多功能激光瞄准测头。详细介绍了测头的光学系统工作原理和设计思路,采用自适应控制方法实时调节激光光强使其可以适应不同光学特性表面的瞄准测量,并进行了多功能测头的重复性瞄准测量、灵敏度测量、倾角跟踪实验。实验结果表明,该测头重复性瞄准测量不确定度优于1 μm,测量灵敏度可达30 mV/μm,激光跟踪瞄准被测曲面倾角可达25°,能满足三坐标测量机的使用要求。该测头具有检测速度快、自动化程度高、瞄准精度高的特点,结合三坐标测量机或者其它测长仪器,能够实现对自由曲面进行快速精确瞄准及轮廓图像瞄准测量,具有广泛的应用前景和实用价值。     

基于基因工程思想的产品族设计及其关键技术研究

通过分析型材断面的尺寸和形状特征的继承关系及型材模块的结构变异,将基因工程的思想用于产品族的开发设计中,并将"型材特征"看作是产品结构信息的"DNA"。借鉴生物学领域基因工程原理,揭示了"型材特征"这种信息流在产品树中的传播规律,在此基础上提出了一种基于基因工程思想的产品基因编码与重组方法。通过对产品族和产品基因DNA的概念以及产品族设计DNA的内涵和研究内容的探讨,指出了支持产品基因工程的关键技术,并以门体型材为例,说明产品族基因工程思想的设计效果。     

激光直写系统中的对准技术应用研究

基于ＩＳＩ－２８０２型激光直写系统原有基片的多图形对准方法，针对衍射光学元件（ＤＯＥ）图形的特点，通过设计合理的对准标记、修改对准识别文件和实验，产生了一套适于ＤＯＥ图形套刻的对准方案。其对准误差小，达到了系统规定指标。并实验研制出了１６位相台阶的ＤＯＥ，取得了良好的效果。     

Binary beam splitter

We propose a method for designing a diffractive beam splitter that enables the diffraction orders to be uniformly distributed within a required elliptic region. The performance of the designed optical element is demonstrated experimentally.     

Design and plasma deposition of dispersion-corrected multiband rugate filters

Inverse Fourier transform method has been commonly used for designing complex inhomogeneous optical coatings. Since it assumes dispersion-free optical constants, introducing real optical materials induces shifts in the position of reflectance bands in multiband inhomogeneous minus (rugate) filters. We propose a simple method for considering optical dispersion in the synthesis of multiband rugate filter designs. Model filters designed with this method were fabricated on glass and polycarbonate substrates by plasma-enhanced chemical vapor deposition of silicon oxynitrides and SiO2/TiO2 mixtures with precisely controlled composition gradients.     

集成光学非球面消球差双凸波导透镜的研制

针对微透镜制作采用的球透镜研磨,多组分玻璃基板离子交换,结晶化玻璃基板光热法,本文提出非球匠消球差双凸波导透镜设计、制备及参数测试方法.该方法根据集成光学原理,研制了一种非球面消球差双凸波哥透镜.该透镜数值孔径大,放大倍数高,接近衍射极限,采用光刻、复制工艺,结构简单,一致性好.实验结幂表明,NA=0.35,β=6.932,光强分布与理论值一致,达到设计要求.     

Optical implementation of the hopfield neural network with matrix gratings

We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.     

Improved retrievals of the optical properties of cirrus clouds by a combination of lidar methods

We focus on improvement of the retrieval of optical properties of cirrus clouds by combining two lidar methods. We retrieve the cloud's optical depth by using independently the molecular backscattering profile below and above the cloud [molecular integration (MI) method] and the backscattering profile inside the cloud with an a priori effective lidar ratio [particle integration (PI) method]. When the MI method is reliable, the combined MI-PI method allows us to retrieve the optimal effective lidar ratio. We compare these results with Raman lidar retrievals. We then use the derived optimal effective lidar ratio for retrieval with the PI method for situations in which the MI method cannot be applied.     

Basic theory of a four-lens optical system design

The theory and the method of calculation of an optical system based on aberration parameters C, W, P are presented. These parameters define all the aberrations of optical systems. The method is based on the synthesis of multilens systems from the single elements. The formulas for the relationships of increments between the angles of the first paraxial ray and the increments in the basic parameters are introduced. These formulas permit the parameters to vary and correct the aberrations. These angle calculations of the first paraxial ray of a four-lens cemented and uncemented system are presented. It is a method for designing complex optical systems from the initial stage to the final stage with corrected aberrations.     

Simulation method for interference fringe patterns in measuring gear tooth flanks by laser interferometry

We present a ray-tracing-based method for simulation of interference fringe patterns (IFPs) for measuring gear tooth flanks with a two-path interferometer. This simulation method involves two steps. In the first step, the profile of an IFP is achieved by means of ray tracing within the object path of the interferometer. In the second step, the profile of an IFP is filled with interference fringes, according to a set of functions from an optical path length to a fringe gray level. To examine the correctness of this simulation method, simulations are performed for two spur involute gears, and the simulated IFPs are verified by experiments using the actual two-path interferometer built on an optical platform.     

Infrared zone-scanning system

Challenges encountered in designing an infrared viewing optical system that uses a small linear detector array based on a zone-scanning approach are discussed. Scanning is performed by a rotating refractive polygon prism with tilted facets, which, along with high-speed line scanning, makes the scanning gear as simple as possible. A method of calculation of a practical optical system to compensate for aberrations during prism rotation is described.