便携式泰曼格林型干涉仪装调方法研究

 为满足光学系统对高精度检测的要求,依据一种新型便携式干涉仪的设计方案,研究了装调方法。该型干涉仪基于改进的泰曼-格林光路结构,其设计测试精度达到λ/10（P-V,λ=630 nm）,具有参考镜离轴、体积小巧、便携、精度较高、成本低及便于批量装备等新特点。针对该新型干涉仪的结构特点,研究了以两个互相垂直的光轴为基准对整体结构进行装调的新方法,并用装调完善的干涉仪进行了实测试验和比对试验。试验结果表明,该新型干涉仪器对已知面型精度为λ/10（P-V,λ=630 nm）的标准球面镜进行检测,其精度可达到0.09 λ;在相同的测试条件下进行比对实验时,该新型干涉仪对普通标准球面镜的检测结果为0.053 λ（RMS,λ=630 nm）,ZYGO干涉仪的检测结果为0.051 λ（RMS,λ=632.8 nm）,两者测量能力较为接近。采用新装调方法进行装调的该新型便携式干涉仪的实际检测精度达到了设计要求,新装调方法可以满足该新型干涉仪的指标要求。     

利用计算机辅助装调检测矩形大口径离轴非球面的方法研究

通过非球面的零位补偿法,完成了对矩形大口径离轴非球面镜的检测。先用光学设计软件Zemax从理论上分析了在检测中会出现的现象,并结合计算机辅助装调技术,确定在检测过程中相对敏感的自由度,然后控制这些量,使补偿器和非球面的相对关系与理论设计相吻合,在Zygo相位干涉仪上测得最终结果。在λ=632.8nm时,中心圆口径与两个边缘圆口径面形误差RMS分别为0.022λ,0.037λ,0.032λ。检测结果,达到预期目的。     

VIRGO mirrors: wavefront control

The Franco-Italian VIRGO program to detect gravitational waves requires large mirrors whose optical properties are extremely severe: absorption and scattering <1ppm at 1064nm, wavefront homogeneity of 9nm RMS on Ø100mm. To achieve this performance on the wavefront, we have developed an experimental method to correct the wavefront shape to be as plane as possible. A thin silica layer is added through a mask by sputtering, where it is necessary on the surface, on the last layer of the multilayer. A phase retardation is produced. The wavefront is measured before and after correction with a Zygo interferometer. The first test has been done on Ø80mm mirror at 633nm. The wavefront peak to valley goes from 34 to 14nm. At this level, we are limited by the interferometer accuracy and repeatability. The optical property modifications due to the corrective coating are small (at 1064nm) or easy to overcome. The corrected wavefront includes at the moment the reference flat of the interferometer, so the measurements are not absolute. But the feasibility of this correction method is proved and it is powerful.     

Finite element analysis on a circular wedge prism with 400 mm diameter

The paper comprehensively analyzes the distortions of a circular wedge prism with 400 mm diameter in a scanner by method of optical-mechanical-thermal integrating analysis. The structure and intensity of the prism assembly is verified and checked, and the surface deformations of the prism under gravity load, as well as the thermo-elastic distortions of the prism, are analyzed in detail and evaluated, which is finally contrasted with the measured values of Zygo Mark interferometer. The results show: the maximal distortion of the prism assembly is 10 nm magnitude and the maximal stress is 0.441 Mpa, which has much tolerance to the precision requirement of structure and the admissible stress of material; the influence of heat effect on the surface deformations of prism is proved to be far greater than the influence of gravity load, so some strict temperature-controlled measures are to be considered when the scanner is used.     

Zygo interferometer for measuring refractive index of photorefractive bismuth silicon oxide (Bi12SiO20) crystal

An application of the Zygo system for measuring the refractive index of optical materials such as bismuth silicon oxide (BSO) having a higher value of the refractive index than that of glass is presented. The setting accuracy is found to be of the order of 1 μm in the Zygo phase measuring interferometer. The mean value of refractive index of BSO crystal measured by the interferometer for several samples of thickness in the range of 3–9 mm is 2.542 at a wavelength of 632.8 nm. The accuracy of measurement is ±0.002. It is possible to achieve an accuracy of ±0.0003 for a sample of thickness of 30 mm in the measurement of refractive index due to high setting accuracy of the Zygo system.     

椭圆形平面镜的高精度面形重构技术

为了实现大口径椭圆形光学平面镜的高精度面形测量,提升大口径望远镜系统的像质,本文对椭圆形平面反射镜面形的绝对检测算法进行了研究。首先,对椭圆形镜面进行了多项式正交化拟合研究。接着,对绝对检测算法进行了理论研究,利用正交化绝对检测算法可以有效分离参考镜与待测镜的面形误差,从而实现待测椭圆形平面镜面的高精度面形重构。为了证明上述方法的实际检测精度,本文对250 mm×300 mm的椭圆形镜面进行了绝对检测模拟与检测实验。对参考镜面形精度不高的情况进行了仿真计算,实验中利用光阑在Zygo300 mm口径标准平面镜头中选取250 mm×300 mm椭圆形检测区域,采用150 mm口径Zygo干涉仪对上述椭圆形区域完成绝对检测,并基于上述正交化绝对检测算法对椭圆形平面镜实现了面形重构。实验结果表明,利用本文所述方法可以实现参考镜与椭圆形待测镜面的面形误差分离,绝对检测结果的残差图RMS(Root-mean square)值为0.29 nm,证明了本文所述方法的可行性。利用上述方法可以实现椭圆形平面反射镜的高精度面形重构。     

激光直写制作的小F数连续浮雕衍射透镜轴向聚焦特性分析

为确定卷积效应以及深度制作误差对小F数连续浮雕衍射透镜(DOE)轴向聚焦特性影响,基于瑞利-索末菲衍射理论建立了激光直写制作的连续浮雕衍射透镜非旁轴近似轴向光强分布模型.该模型考虑了连续浮雕衍射透镜的轴向衍射聚焦特性与透镜结构参数、写入光斑尺寸和扫描间距以及深度制作误差的关系,克服了傍轴近似条件下传统模型的不精确性.为验证模型的正确性,用激光直写制作了设计波长为441.6 nm,F数为4以及相位匹配因子为3的连续浮雕衍射透镜,并测试了波长441.6 nm激光入射时透镜的轴向聚焦特性.实验与分析表明,该模型分析结果与实验测试结果符合,从而证实模型的有效性,为激光直写制作的小F数连续浮雕衍射透镜的应用提供了理论依据.     

基于子孔径拼接技术的大尺寸光学材料均匀性检测系统

为实现大尺寸光学材料折射率均匀性的高精度、低成本检测,提出一种基于子孔径拼接技术的干涉绝对测量方法,并研制了一套由Zygo干涉仪、五维气浮调整平台、子孔径拼接软件、计算机等组成的测量计算系统。待测件安放在精密的五维气浮调整架上,通过移动调整架来对各个子孔径区域进行精密检测,再利用子孔径拼接软件自动拼接计算出全口径待测件的光学均匀性分布。对直径为300mm的石英待测件进行了口径为180mm的8个子孔径拼接检测实验,并将拼接所得结果与全口径干涉仪直接测量的结果进行了分析和比较,波面峰谷值相对误差为0.21%,光学均匀性值相对误差为0.23%,精度与大口径干涉仪直接测量的精度相当,实现了绝对检验下的平面类波前子孔径拼接技术的实用化。整套系统集光、机、电、算于一体,操作简便,测量精度高。     

二次非球面镜检测中基于波前等高线图的调整方法

为了提高非球面光学元件的检测精度及效率,缩短调整环节的时间,分析了非球面干涉检测过程中被检非球面镜的调整误差对检测结果波前信息的影响,提出利用波前等高线图走势准确判断调整方向的调整方法。建立调整方向与被检镜失调量之间的关系,并利用光学设计软件Zemax仿真模拟检测光路,结合二次非球面镜的光学公差分析判断调整量的大小。基于该调整方法,利用Zygo激光干涉仪对口径为50 mm的双曲面进行检测,最终检测结果是RMS为0.014 ,实验表明该方法简单、可行。     

Measurement accuracy verification of aspheric surface test with computer-generated hologram

A convex aspheric surface using a computer-generated hologram(CGH) test plate fabricated with novel techniques and equipment is tested.However,the measurement result is not verified via comparison with other methods.To verify the accuracy of the measurement,a perfect sphere surface is measured by the following.The measurement result is quantified into four parts:the figure error from the tested spherical surface;the figure error from the reference spherical surface;the error from the hologram;and the adjustment error from misalignment.The measurement result,removed from the later three errors,shows agreement to 4-nm RMS with the test by Zygo interfermeter of the same surface.Analysis of the CGH test showed the overall accuracy of the 4-nm RMS,with 3.9 nm from the test plate figure,0.5 nm from the hologram,and 0.74 nm from other sources,such as random vibration,various second order effects,and so on.Thus,the measurement accuracy using the proposed CGH could be very high.CGH can therefore be used to measure aspheric surfaces accurately.     

菲索干涉仪中精确移相的实现

为了实现移相式菲索干涉仪对光学元件面形的高精度测量,建立了干涉仪同步采集移相系统,并对精确移相方法进行了研究。介绍了移相系统的构成和工作原理,计算了测量过程中移相器的速度。针对PZT移相器在移相过程中会引入离焦误差,并存在加速段和减速段的问题,详细设计了移相器的行进过程。最后,对移相器的性能进行了标定。在改造后的干涉仪上开展了重复性验证实验,结果表明：干涉仪可以获得λ/11 340的RMS测量重复性。对改造后干涉仪与Zygo公司生产的Verifire XP/D干涉仪的测量精度做了比对实验,结果显示：相同元件下两者测量结果的面形RMS之差约为0.9 nm,表明提出的移相系统及移相方法在重复性和准确度方面都能满足纳米级面形测量的要求,为研制高精度移相干涉仪奠定了基础。     

Zygo interferometer for measuring refractive index of liquids and its application for heavy water analysis

The Zygo interferometer for measuring refractive index of liquids such as heavy water is presented. The accuracy of measurement in the refractive index of liquids is found to be ±0.0002 in the Zygo interferometer. An application of Zygo interferometer for heavy water analysis is also presented. The interferometer is found to be useful for determining the percentage purity of heavy water with an accuracy of ±5% in the purity range of 0–100%.     

13.9 nm马赫贞德干涉仪用软X射线分束镜研究

 介绍了13.9 nm马赫贞德干涉仪用软X射线分束镜的设计、制备与性能检测。基于分束镜反射率和透过率乘积最大的评价标准,设计了13.9 nm软X射线激光干涉实验用多层膜分束镜。采用磁控溅射方法在有效面积为10 mm×10 mm、厚度为100 nm的Si3N4基底上镀制了Mo/Si多层膜,制成了多层膜分束镜。利用X射线掠入射衍射的方法测量了Mo/Si多层膜的周期。用扩束He-Ne激光束进行的投影成像方法定性分析了分束镜的面形精度,利用光学轮廓仪完成了分束镜面形精确测量。利用北京同步辐射装置测量了分束镜反射率和透射率,在13.9 nm处,分束镜反射率和透过率乘积达4%。使用多层膜分束镜构建了软X射线马赫贞德干涉仪,并应用于13.9 nm软X射线激光干涉实验中,获得了清晰的含有C8H8等离子体电子密度信息的动态干涉条纹。     

利用环形子孔径拼接法检测非球面反射镜

为解决高精度检测非球面反射镜的难题,提出利用Zygo干涉仪完成非球面环形子孔径检测。通过移动待测非球面,使得由干涉仪产生的参考球面波,以不同的曲率半径匹配待测非球面的各个环带区域,分别测试每个环带,进而完成对整个非球面的拼接检测。以双曲面反射镜为例进行拼接检测,并搭建辅助光路,利用无像差点法对拼接结果进行验证。验证结果表明:该方法测量误差小于1/20 （=632.8 nm）。     

Design of a MEMS micromirror actuated by electrostatic repulsive force

A microelectromechanical system (MEMS) micromirror actuated by electrostatic repulsive force is demonstrated. The design is based on the principle that an asymmetric electric field produced by special layout of the electrodes can generate a repulsive force, which moves the mirror surface upwards. The factors affecting the magnitude of the driving force of the micromirror actuator are analyzed by FEA. The prototype is fabricated using a commercial available surface micromachining process and successfully tested using a Zygo NewView7300 interferometer. The displacement of the micromirror reaches 1.2 μm at 60 V.     

A compact optical heterodyne interferometer by optical integration and its application

A compact high-resolution optical heterodyne interferometer combining a two-frequency light module and a minute optical system is described. The light module, which generates two independent frequencies of light, is fabricated by proton exchange method on LiNbO₃ substrate. We report an experiment evaluating measurement accuracy using a micro-displacement measurement system which incorporates this interferometer. Results of the experiment with a standard thickness sample show high thermal stability with maximum measurement error of 1.8 nm at a temperature from 19°C to 33°C. The system was used to measure the hysteresis of a piezoelectric element for displacements of several nm, thereby making it possible to analyze the system quantitatively in practice.     

Fast fabrication of super-hydrophobic surfaces on polypropylene by replication of short-pulse laser structured molds

A new two-step method, facilitating the rapid generation of super-hydrophobic surface structures via parallel laser processing followed by a replica generation by injection molding is reported. A self-made fused silica-based diffractive optical element (DOE) is applied to distribute the laser energy into a 25×25 dot matrix. This DOE is used as a transmission mask for surface ablation of metal molds, applying short-pulse UV laser pulses. In a subsequent process step, replicas of the processed stamp are produced by variothermal injection molding, enabling the mass production of the surface pattern on plastics parts. The resulting topography facilitates a super-hydrophobic behavior of the fabricated components.     

凝视型长波红外折衍混合光学成像系统设计

设计了一套折衍混合凝视红外热成像光学系统.该系统工作波段为8~12 μm, F数为1,全视场达12°, 总长140 mm,两个透镜均采用锗材料。衍射器件制作在第二片透镜的凸面上，可以采用金刚石车削技术进行加工．该系统成像质量接近衍射限并且相对折射系统更好地校正了色差.     

超光滑光学表面粗糙度的测定

讨论了如何确定及消除光学轮廓仪的系统误差,进而测定超光滑光学表面粗糙度的方法及结果。在Ｚｙｇｏ Ｍａｘｉｍ ３Ｄ５７００ 表面轮廓仪上使用２－５ ×和２０ ×Ｍｉｒａｕ 物镜测量ｒｍｓ 在０－３ｎｍ 左右的超光滑硅片,通过对每个取样区域数据１６ 次相位平均,再对多个取样区域高度数据平均,消除了仪器的系统误差,使超光滑光学表面粗糙度得到精确测量。并使用其它光学轮廓仪对样品做了验证测量。作为比较,在同样条件下测量了０－８ｎｍ 左右的光滑硅片。     

利用子孔径拼接法测量大口径凸面反射镜

在简要分析各种检测大口径凸球面方法优缺点的基础上,提出了利用子孔径测量凸面反射镜的新方法,利用干涉仪标准球面波前依次干涉测定大口径镜面上各个区域的相位分布,通过子孔径拼接算法即可求解得到镜面全口径面形信息。对该方法的基本原理和实现步骤进行了分析和研究,建立了大口径拼接检测算法数学模型,设计并研制了大口径反射镜拼接检验装置。结合实例对加工过程中的口径为300 mm的碳化硅凸面反射镜进行了9个子孔径的拼接干涉测量,并将检测结果与全口径面形测量结果进行对比,两种方法残差的PV值和RMS值分别为0.102 和0.009 (=632.8 nm)。