Offner补偿器的结构设计与装调

针对90nm节点光刻投影镜头中使用的非球面存在高次项,且与理想球面偏离量较大的特点,基于像差补偿理论,设计了一种三片式结构的Offner补偿器来实现非球面的高精度检测。采用等量轴向球差补偿非球面各阶系数的方法,主动引入一定量的轴向球差,补偿光线在非球面法线方向的偏离量。结果表明,初级像差和高级像差可很好地平衡,使剩余像差很小;MTF远远超过衍射极限;系统工作波长为632.8nm,F数为1.64,均方波差RMSλ/1250;系统轴向像差0.47μm,满足基本干涉成像条件;各方面指标均满足高精度检测补偿器的设计要求。最后,根据现有检测装置的精度对所设计的结果进行了公差分析,给出了较宽松的公差容限。公差分配后,系统综合残余波像差0.00727λ,满足系统装调精度要求。     

Offner补偿器的结构设计与装调分析

90nm节点光刻投影镜头中使用的非球面都存在高次项,而且对理想球面的偏离量较大。本文设计了一种基于三片式结构的Offner补偿器,实现了对高次非球面面形的高精度检测。采用等量轴向球差补偿非球面各阶系数的方法,主动引入一定量的轴向球差,补偿光线在非球面法线方向的偏离量,结果表明：对初级像差和高级像差很好的平衡,使剩余像差很小;MTF 远远超过衍射极限,系统工作波长为632.8nm,F数达到1.64,均方波差RMS<λ/1250。满足了高精度检测补偿器的设计要求。最后根据现有的检测装置的精度对所设计的结构进行了公差分析,给出了较宽松的公差容限。     

用校正法提高补偿器检测法的精度

研究了一种测量、分离补偿法检测补偿器非圆对称误差的技术,这种技术基于波面误差可用泽尼克圆多项式来表述。通过使补偿器或被测非球面绕系统光轴旋转到多个不同的角度,得到多个测量结果,根据这些测量结果,计算得到由补偿器误差带来的波面误差的非圆对称项泽尼克圆多项式系数,接着根据这些非圆对称项泽尼克圆多项式系数制作一个校正文件对非球面的测量结果进行校正,利用该技术可有效减轻对补偿器材料、加工及装校的苛刻要求,提高测量精度。实验结果表明:对某一被测非球面不用该技术时测量结果为0.105 λ(RMS),应用此技术后的测量结果为0.026 λ(RMS),且被测面在几个任意不同角度时的测量结果相差只有0.001 λ(RMS),效果很好。该技术已被应用到实际的双曲面凸面反射镜的测量中。     

微机控制光学非球面加工

光学非球面加工控制系统是由主机IBM-PC与直接控制(单板机)两级组成的分布式控制系统。IBM-PC完成对非球面面形误差的分析与计算进而自动生成加工程序;单板机控制装置控制抛光机,带动抛光模按加工程序要求,在非球面表面运动。本文主要介绍数控装置的实现,系统安全,断电保护措施以及IBM-PC与单板机双机通讯等。 1.系统的组成及工作原理在光学系统中,应用非球面能够校正像差,改善像质,简化光学系统结构,减轻重量。因而在航空航天光学系统,天文观测,红外技术等诸多方面都有广泛的应用价值。但由于非球面加工与检测的困难,使其应用受到阻碍。对高精度的大型非球面,目前国内一般采用普通研磨抛光法,用刀口仪测量根据阴影图来定性判断误差,在抛光机上,由人工修正抛光模,来控制加工精度。     

Ф1．2mF／1．5抛物面主镜补偿器

用于Ф1．2mF／1．5主镜面形检验的补偿器,需要补偿0．087mm的非球面度,并满足0．033λ（RMS）面形检测要求。介绍了该补偿器的设计、误差分析、加工、标校及最终主镜检测的情况。主镜检测前用计算全息（CGH）对补偿器标校显示：补偿器产生的抛物面面形误差为0．012λ（RMS）,二次曲面常数K的误差为0．0064％;主镜最终补偿检测结果为：面形误差0．027λ（RMS）,二次曲面常数K的误差为0．0306％,与分析的结果相符。结果表明,补偿器设计合理,建立的误差分析原则和方法可行,加工质量可靠,为更大口径高陡度非球面主镜的补偿检验奠定了坚实基础。     

大口径碳化硅材料凸非球面反射镜的检验

为了实现某大口径碳化硅材料凸非球面反射镜检验,研究了无像差点法以及补偿检验法方案.经过比较优选,确定选用补偿检验方案并专门设计了高精度大口径非球面补偿器,设计精度为PV:0.008 2λ,RMS:0.002 9λ(λ=632.8nm).采用会聚光束,使用大口径数字干涉仪进行凸非球面正面检测,最终检测结果为0.022λ(RMS).所述补偿器的设计方法和要求具有普遍性,设计结果也可用于同类型大口径凸非球面检验用补偿器的设计.采用该方法提高了凸非球面检测精度,并且在凸非球面镜的材料选择、结构设计、支撑方式等方面提供了更多的优化空间,为新型光学材料在凸非球面反射镜的应用奠定了基础.     

Φ1.2m F/1.5抛物面主镜补偿器

用于Φ1200 F/1.5主镜面形检验的补偿器,需要补偿0.087mm的非球面度,并实现0.033λ（RMS）面形检测要求。详细介绍了该补偿器的设计、误差分析、加工、标校及最终主镜检测的情况;用于主镜检测前用计算全息（CGH）对补偿器标校显示：补偿器产生的抛物面面形误差为0.012λ（RMS）,二次曲面常数K的误差0.0064%;主镜最终的补偿检测结果为：面形0.027λ（RMS）,二次曲面常数K的误差0.0306%,与分析的结果相符合。结果表明：补偿器设计合理,建立的误差分析原则和方法可行,加工质量可靠,这将为更大口径高陡度非球面主镜的补偿检验奠定坚实基础。     

非球面模芯ELID磨削系统的研制

针对非球面模芯超精密磨削加工问题,研制了在线电解修锐(ELID)磨削系统。该系统应用平行法磨削原理,用整形后的球头砂轮进行非球面模芯的超精密磨削加工;利用非球面模芯工件本身的导电性能,以铸铁结合剂CBN砂轮作为阳极,以模芯本身作为阴极,通过ELID电源参数(电流、电压、占空比)的合理选择,解决了CBN球头砂轮的修锐,稳定地实现了小口径非球面模芯的ELID超精密磨削加工。     

大口径碳化硅材料凸非球面反射镜检验技术

为了实现某大口径碳化硅材料凸非球面反射镜检验,研究了无像差点法以及补偿检验法方案,经过方案比较优选,确定选用补偿检验方案并专门设计了高精度大口径非球面补偿器,设计精度为PV：0.0082,RMS：0.0029（=0.6328nm）,采用会聚光束、使用大口径数字干涉仪进行凸非球面正面检测,采用该方法进行检验凸非球面反射镜最终检测结果为0.022（RMS）本文所述补偿器的设计方法和要求具有普遍性,设计结果也可用于同类型大口径凸非球面检验用补偿器的设计。采用该方法提高了凸非球面检测精度,并且在凸非球面镜的材料选择、结构设计、支撑方式等方面提供了更多的优化空间,为新型光学材料在凸非球面反射镜的应用铺平了道路。     

高精度非球面制造系统控制软件的设计

根据高精度非球面制造及测量的需求,设计并实现了高精度非球面制造及测量系统的控制软件。系统基于工控PC机和Windows98操作系统,并选用Delphi 6.0和Visual Fortran作为开发工具。系统采用在线误差补偿加工技术,可选择平面砂轮和圆弧砂轮两种加工方式,达到加工高精度光学非球面镜的要求。     

Ф420mm高次非球面透镜的加工与检测

介绍了Ф420mm熔石英高次非球面透镜的加工与检测方法。对现有数控加工工艺进行了优化,通过分工序加工方式,依次采用机器人研磨、抛光和离子束修形技术完成了透镜的加工。进行非球面透镜检测时,考虑透镜的凹面为球面,利用球面波干涉仪对其面形进行了直接检测,剔除干涉仪标准镜镜头参考面误差后,透镜凹面的精度达到0.011λ-RMS;针对透镜的凸面为高次非球面,采用基于背后反射自准法的零位补偿技术对其进行面形检测,其精度达到0.013λ-RMS。最后,采用一块高精度标准球面镜对加工后透镜的透射波前进行了自消球差检测,得到其波前误差为0.013λ-RMS。试验结果表明,非球面透镜各项技术指标均满足设计要求。所述工艺方法亦适用于更大口径的非球面透镜及其他类型非球面光学元件的高精度加工.     

小口径双非球面硫系玻璃镜片精密热压成形模具制造

将小口径双非球面硫系玻璃镜片精密热压成形过程的有限元分析与模具非球面轮廓预测及补偿相结合,提高热压成形模具的制备效率与精度,满足该类镜片高精度批量制造的需求.根据硫系玻璃热压过程中的热传递、黏弹性、应力松弛行为与结构松弛特性的分析,获得玻璃高温热力学性能参数,建立镜片热压成形的有限元模型;对仿真获得的镜片非球面轮廓曲线...     

Improvement of form accuracy and surface integrity of Si-HDPE hybrid micro-lens arrays in press molding

Press molding of silicon (Si)/high-density polyethylene (HDPE) composite is an important technology for producing thin hybrid infrared (IR) optics with microstructures. In this research, Si-HDPE hybrid micro-lens arrays were press molded under various conditions, and the form accuracy and surface integrity of the molded lenses were evaluated. Air trapping occurs inside the micro-lens cavities during molding in a non-vacuum environment, which leads to severe surface defects. To investigate the air trapping phenomenon, a new in-situ observation system was developed which enables real-time direct observation of the molding process. From the in-situ observations, it was found that air traps were formed among the HDPE pellets during melting, and an increase in the pressing force will increase the pressure of the trapped air, forming trenches on the lens surface. The trapped air also impacts the mold coating, causing trench formation on the coating surface. To minimize air trapping, the molding temperature, and pressing force must be strictly controlled. By performing press molding in a vacuum environment, trench formation was completely eliminated. Moreover, polymer shrinkage compensation was performed to improve the lens form accuracy.     

Airbag tool polishing for aspherical glass lens molds

This paper presents a novel airbag tool polishing technique for small aspherical glass lens molds. For a mold material such as tungstencarbide, an ultra-precise grinding technique is used to generate the aspherical surface. However, the residual tool marks of the spiral pattern and scratch unavoidably develop on the mold surface. Therefore, post-polishing is required to obtain the optical surface. Footprinting by the superposition method without trajectory control was applied to polish the finely ground aspherical lens mold. A white light interferometer confirmed the tool mark removal effect. The final surface roughness was Ra 2nm. Microscopic observation also showed a cleaner surface without scratches.     

Precise bi-arc curve fitting algorithm for machining an aspheric surface

With the rapid development of the information/image system and aero-space industries, high quality optic aspheric surface lenses play an increasingly important role for completion of the functionalities. Aspheric lenses are non-spherical surfaces having rotation symmetry about the lens axis. The aspheric lens has various shapes according to its application and often requires tens nanometer order form accuracy since surface roughness and form accuracy play essential roles in the functional performance of the optical products. Interpolation of the aspherical surface path must precisely meet the allowable tolerance. Linear interpolation of the aspheric surface path for CNC machining generates an enormous amount of NC code to satisfy the extremely small tolerance, and produces scallops on the machined surface due to the acceleration and deceleration of the tool during every linear motion. Alternatively, interpolations with bi-arcs are used. In this paper, in order to minimize the error induced by the cutting tool path and to shorten the calculation time of interpolation, a precise -arc interpolation method is proposed. The developed algorithm of bi-arc interpolation meets the given tolerance precisely. This is guaranteed by an analytical proof and error maps. Another advantage is its ability to calculate about five times faster than the existing arc interpolation, since iterative calculations for the maximum error can be omitted. The developed algorithm has been used for the precise aspheric machining.     

主动式PSD自动对焦光学系统设计

在照相机主动式PSD自动对焦系统中，发射透镜与接收棱镜要求口径大、球差小，价格低、体积小，保证PSD上光斑小而且边缘清晰。本文认为，非球面单片透镜适合该系统。本文导出了非球面透镜的设计方法和计算实例，并给出了AF光学系统总体设计实例。     

薄型非球面弹性变形面形复制加工技术研究

提出一种新型非球面加工技术——弹性变形面形复制加工技术,该技术综合利用光学玻璃材料的线弹性特性以及面形复制加工机理,将复杂的非球面加工转变为简易的平面加工,适合加工薄型大曲率半径非球面。阐述弹性变形面形复制加工技术的基本机理,随后以直径为40 mm、顶点曲率半径为2 500 mm的抛物面作为目标面形,通过有限元仿真确定使工件与靠模紧密贴合所需的工件最小去除厚度,建立加工过程的材料去除模型,并由此确定加工时间。在所搭建的弹性变形面形复制加工系统上进行加工试验,试验结果证明所建立材料去除模型有效。最终工件加工面形精度为PV 0.62 μm。对加工面形精度影响因素进行分析,并提出改进工件加工面形精度的措施。     

液体透镜的发展趋势

由于光电仪器日益小型化和轻量化,从而在系统中越来越多地采用了一些像非球面和自由曲面光学零件、折射—衍射混合光学零件等新型的光学零件。但是,随着镜头的变小,在很小的空间内已无法使用原有的机械方法实现对焦和变焦的功能。这就是研发小尺寸、可变焦距的液体透镜的目的。文中系统地介绍了通过调整电压或其他物理量的方法,改变介质的折射率(液晶透镜)或面型(液体透镜),从而可以改变其焦距的透镜。目前基于电湿润法原理的液体透镜已经商品化,并已经开始大量的用于手机的照相光学模组中,实现了对不同距离的物体进行对焦。但由于液体透镜的研发仅仅是开始,还有很多的性能要改善、还有很多的关键课题等待去解决。     

A new method for aspherical surface fitting with large-volume datasets

In the framework of form characterization of aspherical surfaces, European National Metrology Institutes (NMIs) have been developing ultra-high precision machines having the ability to measure aspherical lenses with an uncertainty of few tens of nanometers. The fitting of the acquired aspherical datasets onto their corresponding theoretical model should be achieved at the same level of precision. In this article, three fitting algorithms are investigated: the Limited memory-Broyden-Fletcher-Goldfarb-Shanno (L-BFGS), the Levenberg–Marquardt (LM) and one variant of the Iterative Closest Point (ICP). They are assessed based on their capacities to converge relatively fast to achieve a nanometric level of accuracy, to manage a large volume of data and to be robust to the position of the data with respect to the model. Nevertheless, the algorithms are first evaluated on simulated datasets and their performances are studied. The comparison of these algorithms is extended on measured datasets of an aspherical lens. The results validate the newly used method for the fitting of aspherical surfaces and reveal that it is well adapted, faster and less complex than the LM or ICP methods.