Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Stratospheric Wind Speed Measurement Key Technology Research Based on Direct Detection Lidar
No full text多普勒激光雷达探测体制中，直接探测相对于相干探测具有可测量大气分子多普勒频移的显著特点，特别适合平流层大气的风速探测,因此在该大气层多普勒探测中具有很大的研究价值和重要应用。 基于低平流层大气风速的探测目的，本文的主要研究工作如下： 首先比较分析和选择了适合于低平流层大气风速测量的鉴频器，即以双通道FP干涉仪和Fizeau干涉仪这两种干涉仪为鉴频器进行了鉴频器的优化和参数选择，分别对两个鉴频器测量大气风场的灵敏度、信噪比和测量误差进行了仿真计算和比较。依据1m/s的测量误差为鉴频器选择标准，分别模拟两种鉴频器所在多普勒激光雷达系统中的探测能力，资源和硬件配置；然后优选了双通道FP干涉仪作为鉴频器能满足探测误差要求。而Fizeau干涉仪作为鉴频器的多普勒激光雷达系统虽然省却了锁频子系统，但需要高灵敏度和高度读取速率的多元线阵探测器才可以实现，而该探测器还没有成熟的产品，随着探测器技术的成熟将来可得到应用。最后利用低平流层大气参数优化设计了一套Fizeau干涉仪作为鉴频器的激光雷达系统参数，一套FP干涉仪作为鉴频器的激光雷达系统参数。 然后根据选定优化的多普勒激光雷达系统参数，开展风速探测误差理论分析。根据大气S6模型，模拟仿真了温度测量精度，压力测量精度，平台姿态测量精度（俯仰角、翻滚角和航向角）等多种误差源导致的速度测量误差，为激光雷达测量能力评估提供了参考，例如：温度测量误差导致的速度误差为2.9‰。 最后，基于双FP干涉仪设计了双边缘锁频技术方法。该方法的特殊优势是探测通道和锁频通道不再分开，同时具有风速探测和稳频的功能，不会造成额外的误差。同时介绍了种子激光器的碘分子稳频实验，实现了种子激光高精度频率稳定控制。Doppler lidar direct detection system compared to the coherent detection has distinctive features of detecting atmospheric molecules scattering signal Doppler frequency shift, especially for stratosphere atmosphere wind speed measurement ,which has great research values and important applications. Based on low stratosphere atmospheric wind speeds detection purpose, the main research work of this thesis are presented as the followings: Firstly, through comparative analysis, we choose frequency discriminator that is suitable for low stratosphere atmospheric wind speed measurement. According to the dboule Fabry-Perot(FP) interferometer and Fizeau interferometer frequency discriminator parameters optimization, the atmospheric wind field measurement sensitivity, signal-to-noise ratio and measurement error are calculated and simulated. The wind speed measurement error of 1 m/s is acted as the discriminator selection criteria. The two kinds of Doppler frequency discriminators detection ability and hardware parameters design of the two discriminators are presented. And the double FP interferometer is acted as the preferred discriminator for high accuracy wind speed measurement. Although Fizeau interferometer system needn’t lock the frequency, high sensitivity and high frame rate of the linear array detector have to be met., which can be realized in future. The part of the main innovation point is that by using low stratosphere atmospheric model parameters, we have got the optimized Fizeau interferometer and FP interferometer discriminator parameters. Then, according to atmospheric S6 model, wind speed errors caused by a variety of error sources, such as, temperature measurement precision, pressure measurement precision, platform attitude (pitching Angle, roll Angle and heading Angle) measurement precision are simulated. They provide reference for the laser radar measurement capability assessment. And the velocity error caused by temperature error is 2.9 ‰. At last, locking frequency technology method based on double FP interferometer technology method is analyzed. The special advantages of the method is that the detection channel and the frequency locking channel are the same, which have the function of wind speed detection and laser frequency stabilization at the same time, which will not cause additional error. Also the seeder frequency stabilization experiment based iodine cell absorption line is presented
Application of Modern Optical Detection Technology for Study of the Ancient Chinese Porcelains
No full text中国古代瓷器是我国古代文化和技术的结晶，蕴含着丰富的科技、历史、艺术价值。综合利用现代多种光学检测技术对古代瓷器进行研究，对揭示其产地、年代、制作工艺等综合信息具有重要意义。本文结合光学相干层析 (OCT) 成像技术、便携式能量色散型X射线荧光光谱技术(pXRF)、扫描电子显微镜(SEM-EDS)、光学显微技术(OM)对不同地区出土出水的古代瓷器进行科学分析，进而探讨其分类、产地特征识别、工艺等问题。 论文的主要内容包括以下几个方面： (1)利用光学相干层析(OCT)成像技术研究了南海一号沉船出水的南宋初期景德镇窑和龙泉窑青瓷瓷片的瓷釉断层结构特征，并结合X射线荧光(XRF)光谱分析技术，对比研究了两个窑址青瓷胎釉化学成分差异，进而探讨了瓷釉断层OCT图像特征与釉层化学成分特征之间存在的联系。 (2)将X射线荧光(XRF)光谱分析技术与光学相干层析(OCT)成像技术与相结合，对南澳一号沉船出水景德镇和漳州两地的明代青花瓷瓷片的釉面断层结构特征、胎釉以及青花钴料的化学成分特征进行了分析，对瓷器分类以及产地特征识别等问题进行了研究。此外，还利了OCT技术对景德镇青花瓷局部青花图案进行了OCT 3D扫描，探讨OCT技术对青花纹饰纹理研究的可行性。 (3)结合OCT和XRF技术对河南省宝丰清凉寺、汝州张公巷、大峪东沟出土的青瓷残片样品进行了研究，对比分析了不同产地以及宝丰清凉寺不同时期青瓷的成分和结构的特征差异，进而探讨了河南省出土青瓷断源断代的相关问题。 (4)利用光学相干层析技术(OCT)、光学显微技术(OM)、扫描电镜技术(SEM)等多种技术相结合，分析了瓷器印花和刻花装饰工艺的显微特征、蓝釉红斑钧瓷釉层中的晶体颗粒以及胎釉中间层的化学成分，探索研究了晶体颗粒的物相、钧瓷釉色的致色机理以及胎釉中间层的化学成分特征。Chinese porcelains have a very important significance in scientific archaeology as the double carrier of ancient science and art.Modern optical detection technology analysis is an effective way to reveal the scientific and technical values of ancient Chinese porcelains.In this thesis,versatile techniques including portable energy dispersive X-ray fluorescence spectrometer (pXRF), optical coherence tomography (OCT),scanning electron microscope (SEM) and Optical Microscopy (OM) were used to analyze ancient Chinese ceramic and other relative artifacts excavated from different sites. Based on the results, some issues such as classification,characteristics of the porcelains from different provenance ,production process were discussed. The main contents of this dissertation are listed as the follows: (1)Celadon wares of Jingdezhen and Longquan found in Nanhai No.1 shipwreck which dated to early Southern Song dynasty are analyzed using optical coherence tomography(OCT) and X-ray fluorescence (XRF). The glaze cross-section structures and decorations of celadon wares from Jingdezhen and Longquan kilns are studied firstly by OCT, and then, the chemical compositions of glaze and body of the celadon wares are also obtained and compared. The results show that celadon wares from the two kilns have differences in both glaze cross-section structure and chemical compositions of glaze and body. Moreover, the differences of chemical composition of glaze have a close relationship to that of glaze cross-section structures. (2)In order to reveal comprehensive information and explore scientific methods for classification and provenance study for ancient Chinese blue and white porcelains, X-ray fluorescence (XRF) spectroscopy,combined with optical coherence tomography(OCT), is used to study the glaze cross-section structures of Chinese blue and white porcelains excavated from Nan’ao No.1 shipwreck and dated to Ming dynasty. The characteristics of glaze cross-section structures and chemical compositions of glaze, body and cobalt pigments are obtained. The experimental results show that blue and white porcelain from Jingdezhen kiln and Zhangzhou kiln have differences in both glaze cross-section structure and chemical compositions of glaze, body and cobalt pigments. According to the obvious difference of white glaze cross-section structures and chemical compositions of body and blue pigment, the blue and white porcelains from Zhangzhou kiln can be divided into two types. In addition, this paper shows the decorative pattern of blue and white porcelain of Jingdezhen blue and white porcelain by 3D scanning function of OCT, and indicates that the combination of OCT and XRF is validated as an effective method to study the classification, provenance and access to comprehensive information of ancient Chinese blue and white porcelains. (3)XRF and OCT were applied to characterize the Chinese ancient celadon excavated from Qingliangsi Zhanggongxiang and Dayudonggou in Henan province which were dated to Northern Song Dynasty to Han Dynasty .The characteristics and differences of the celadon which from the different regions in henan and The characteristics and differences of Qingliangsi celadon in different periods are obtained and compared.and then discusses,and then discuss the issues related to origin Analysis and chronology about celadon from Henan province. (4)OCT, SEM-EDS and OM were applied to study the differences of carved process and printing process, the crystal particles in Jun glaze layer and the chemical compositions of middle layer between glaze and body.According to the experimental results, the phases of crystal particles in glaze layer, the coloration mechanism of red Jun glaze and the features of chemical compositions of middle layer between glaze and body were discussed
Pixel-based mask optimization via particle swarm optimization algorithm for inverse lithography
No full textAn efficient pixel-based mask optimization method via particle swarm optimization (PSO) algorithm for inverse lithography is proposed. Because of the simplicity of principles, the ease of implementation and the efficiency of convergence, PSO has been widely used in many fields. In this study, PSO is used to solve the inverse problem of mask optimization. The pixel-based mask patterns are transformed into frequency space using discrete cosine transformation and the frequency components are encoded into particles. The pattern fidelity is adopted as the fitness function to evaluate these particles. The mask optimization method is implemented by updating the velocities and positions of these particles. Simulation results show that the image fidelity has been efficiently improved after using the proposed method
Efficient second harmonic generation in an on-chip high-Q crystalline microresonator fabricated by femtosecond laser
No full textWe report on transiently phase matched second harmonic generation in an on-chip lithium niobate (LN) microresonator fabricated by femtosecond laser direct writing followed by focused ion beam milling. We demonstrate a normalized conversion efficiency of 1.1x10(-3)/mW in the LN microdisk with a diameter of similar to 102 mu m and a thickness of similar to 700 nm
A Novel Method about Online Monitoring Surface Shape of Optical Elements in Continuous Polishing
No full textIn conventional continuous polishing process, the surface shape of work-piece was measured by an optical plane template after being placed in such environment with constant temperature for 1 to 2 hours. During this period, uncertain influence may occur on the polishing pad due to the change of system state. Meanwhile, the regular off-line testing may cause re-processing. In this paper, a new method about on-line monitoring surface shape of optical elements is proposed by the theory of run-sphere, and the change in curvature radius of the work-piece which lead to its radial tilt angle change. The change in work-piece surface shape indirectly obtain by the correction plate small angle with respect to the horizontal, and the angle were detected on line by the high-precision goniometer with the resolution 0.04 ''. According to theoretical calculations, the diameter of 200mm precision work-piece PV value up to 0.02 lambda (lambda = 632.8nm). The fused quartz glass was measured by above method. The test results showed that the surface accuracy and processing efficiency were significantly promoted, and also improving the controllability of surface shape of work-piece based on this method
Mitigation of BSG damage caused by upstream flaw in the final optics assembly
No full textIn high-power laser facilities for the inertial confinement fusion, there are many large-radius optical elements, which inevitably have some flaws on the surface. The flaws can cause optical intensity intensification and therefore damage the optical elements in the downstream, especially for the beam sampling grating (BSG), which is an important element in the final optics assembly. In this paper, several physical models are established to study the optical field enhancement in the BSG position modulated by upstream flaw. Firstly, when only the linear transportation is considered, it is found that there is a peak or valley of the maximum intensity after the focus lens compared with the ideal wave front. Meanwhile the influence of flaw has an effective range. Secondly, when the nonlinear effect of the focus lens is also considered, the peak maximum downstream is much bigger than the one for the linear consideration and the damage risk of the BSG there is much higher too. From the simulation, we can see that it is important to place the BSG in a properly selected position to mitigate the laser induced damage. The results could give some references to the mitigation of BSG damage caused by upstream flaws and the layout of the final optics assembly
Research of Absolute Testing based on N-position Rotations
No full textThe full-aperture and full-frequency absolute surfaces of optical flats are of great significant for industrial applications but hard to achieve. To measure them simultaneously, Kuechel proposed an absolute testing based on N-position rotations by adding a set of measurement data of N-position rotations, in comparison to the traditional four measurements. Algorithm simulation and absolute detection experiments have been conducted before, however, the influence of rotation angle error has not been analyzed, and the full-aperture contrast experiments have not been conducted. In this paper, the influence of rotation angle error was analyzed, and the measurement result is within acceptable range even when the angle error reaches 1 degrees. Moreover, to verify the accuracy of this method, full-aperture contrast experiments were proposed innovatively besides the two linear profiles contrast experiments. The contrast experiments prove the accuracy of the full-aperture absolute measured results, other than the accuracy of the two linear profiles results
基于数控系统的大口径光学元件自动化干涉检测辅助设备
No full text随着光学元件的尺寸越来越大,重量越来越重,精度越来越高,其在搬运、储存以及检测手段等方面造成了巨大难题。本文研制了一种用于大口径光学元件干涉检测的辅助设备,该设备基于数控系统,可根据预设流程,经由移送吊装机构实现了光学元件自静置平台至干涉检测调整平台的自动转运调整过程。相比于一般的人工辅助机械的搬运与调整过程,该设备操作简单便捷,且在转运过程中无需人工参与,从而