铁电单晶Pb(Mg1/3Nb2/3)O3-PbTiO3的高场致应变及其在层叠式驱动器中的应用

通过研究(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMNT)单晶在不同方向、不同组分下高场致应变的特性,确定了〈001〉取向PMNT单晶(29%≤x≤31%)为制作层叠式驱动器的最佳组分范围,这组分的单晶具有高场致应变、低滞后而且性能较稳定的特点.研究结果表明,在保证应变曲线的线性和低滞后的前提下,将近-2kV/cm的负电场能够运用于〈001〉方向的PMNT晶体上. 40层(每片晶片尺寸为7mm×7mm×0.7mm)PMNT层叠式驱动器在电场 -1.5-10kV/cm的驱动下,可以获得38.1μm的纵向位移,负载40N的重量后,位移量减为34μm.     

双压电片变形反射镜样镜的设计与研制

双压电片变形反射镜作为波前校正器具有结构简单、变形量大、成本低及制造周期短的优点,能代替传统分立式变形镜从而降低自适应光学系统的成本.为验证工艺的可行性和了解双压电片变形反射镜的性能,制造了一块20单元的试验样镜.样镜采用了双层压电陶瓷的结构,其中一层作整体离焦电极以校正大幅值的离焦像差.利用Veeco干涉仪测最了样镜单元电极影响函数,分析了其埘前36项Zernike像差的校正能力.结果表明,样镜对离焦像差能获得高达8μm以上的校正量,对其它高阶像差也能适量校正,但校正能力随空间频率升高而降低,显示出其适合校正低阶像差的特性.此外,讨论了不同有效孔径下样镜对Zernike像差的拟合能力.     

1.8m望远镜变形次镜波前拟合能力分析

波前拟合能力分析是变形次镜研制工作的重要组成部分,是基于变形次镜的新型自适应光学系统研制的重要基础.以拟合误差为评价标准,采用有限元计算所得驱动器影响函数对1.8 m望远镜变形次镜四个备选方案进行了泽尼克(Zernike)多项式、Kolmogorov湍流大气畸变相位屏拟合能力分析.结果表明73单元变形次镜波前拟合能力较...     

37-element solar adaptive optics for 26-cm solar fine structure telescope at Yunnan Astronomical Observatory

A 37-element solar adaptive optics （AO） system was built and installed at the 26-cm solar fine structure telescope of Yunnan Astronomical Observatory. The AO system is composed of a fine tracking loop with a tip/tilt mirror and a correlation tracker, a high-order correction loop with a 37-element deformable mirror, a correlating Shack-Hartmann wavefront sensor based on the absolute difference algorithm, and a real time controller. The system was completed on Sep. 28, 2009 and was used to obtain AO-corrected high-resolution solar images. The contrast and resolution of the images are clearly improved after wavefront correction by AO. To the best of out knowledge, this system is the first solar AO system in China.     

20单元双压电片变形反射镜的影响函数有限元分析和实验测量

影响函数是分析双压电片变形反射镜像差校正能力的重要参量,通过建立有限元模型预测实际器件的影响函数,以有限元模型的不断优化替代实际器件的尝试性改进,可以减小构造的盲目性,从而节约研发成本,缩短双压电片变形镜的实用化进程.采用Veeco干涉仪测量了20单元双压电片变形反射镜的影响函数,同时建立有限元模型进行了相应计算,并将计算结果与实际器件的测量数据进行了对比分析.结果表明,相对于实测数据而言,有限元模型计算得出的影响函数在量值上略有偏小,但其形状和峰值位置与测量数据一致性好,两者对前35项泽尼克像差的拟合曲线也基本吻合,各项拟合误差系数之差皆小于0.1.这说明通过不断改进有限元模型实现对实际器件的优化设计是切实可行的.     

中国科学院光电技术研究所的自适应光学研究进展

中国科学院光电技术研究所的自适应光学研究始于1979年。1980年建立自适应光学研究室,在突破了波前校正器(包括变形反射镜和高速倾斜反射镜)、波前传感器、波前处理机和波前控制等关键技术的基础上,研制了一系列自适应光学系统,用于天文望远镜、惯性约束聚变和人眼视觉研究等。     

Influence of low temperature on the surface deformation of deformable mirrors

The two factors which influence the low temperature performance of deformable mirrors(DMs) are the piezoelectric stroke of the actuators and the thermally induced surface deformation of the DM. A new theory was proposed to explain the thermally induced surface deformation of the DM: because the thermal strain between the actuators and the base leads to an additional moment according to the theory of plates, the base will be bent and the bowing base will result in an obvious surface deformation of the facesheet. The finite element method(FEM) was used to prove the theory. The results showed that the thermally induced surface deformation is mainly caused by the base deformation which is induced by the coefficient of thermal expansion(CTE) mismatching; when the facesheet has similar CTE with the actuators, the surface deformation of the DM would be smoother. Then an optimized DM design was adopted to reduce the surface deformation of the DMs at low temperature. The low temperature tests of two 61-element discrete PZT actuator sample deformable mirrors and the corresponding optimized DMs were conducted to verify the simulated results. The results showed that the optimized DMs perform well.     

铁电单晶Pb (Mg1/3Nb2/3)O3-PbTiO3的高场致应变及其在层叠式驱动器中的应用

通过研究(1_x)Pb(Mg_1/3Nb_2/3)O_{3_x}PbTiO3(PMNT)单晶在不同方向、不同组分下高场致应变的特性，确定了〈001〉取向 PMNT单晶（29％≤x≤31%）为制作层叠式驱动器的最佳组分范围，这组分的单晶具有高场致应变、低滞后而且性能较稳定的特点.研究结果表明，在保证应变曲线的线性和低滞后的前提下，将近-2kV/cm的负电场能够运用于〈001〉方向的PMNT晶体上. 40层（每片晶片尺寸为7mm×7mm×0.7mm）PM 关键词： PMNT单晶 场致应变 PMNT驱动器     

First light on the 127-element adaptive optical system for 1.8-m telescope

A 127-element adaptive optical system has been developed and integrated into a 1.8-m astronomical telescope in September 2009.In addition,the first light on a high-resolution imaging for stars has been achieved（September 23,2009）.In this letter,a 127-element adaptive optical system for 1.8-m telescope is described briefly.Moreover,star observation results in the first run are reported.Results show that the angular resolution of the system after adaptive optics correction can attain 0.1 arcsec,which approaches the diffraction limit of 1.8-m telescope at 700-900 nm band.     

Hysteresis compensation of piezoelectric actuator for open-loop control

The hysteresis nonlinearity of piezoelectric actuator is one of the main defects in the control of deformable mirror which is widely used as a key component in adaptive optics system. This letter put forward a roodified Prandtl-Ishlinskii （PI） model in order to precisely describe the hysteresis nonlinearity of piezoelectric actuator. With this proposed model, an inverse-model based controller used for trajectory tracking in open-loop operation is designed to compensate the hysteresis nonlinearity effect. Then, some tracking control experiments for the desired triangle trajectory are performed. From the experimental results, we can see that the positioning precision in open loop operation is significantly improved with this inverse-model based controller.