几种分立式微变形镜的性能模拟与比较

采用形状函数法描述变形镜校正时的曲面,从适配误差、Streh l比两方面比较了四种不同单元排列方式的微变形镜。结果表明方形与砖形排列的微变形镜设计简单,但波前校正性能较差;圆形及蜂窝形微变形镜具有较高的波前校正性能,但设计加工复杂。     

基于单压电变形镜的可控环形焦斑整形

为了实现可控环形焦斑的整形,提出了一套基于单压电变形镜的整形方法。首先结合波前衍射理论和随机并行梯度下降算法模拟迭代出环形焦斑整形所需的调制相位,进而利用波前传感器探测光束的波前信息,控制变形镜重构目标光斑对应的调制相位,实现聚焦光斑的整形。搭建了一套基于62单元单压电变形镜的光斑整形实验平台,采用焦平面上的CCD记录远场聚焦光斑。实验结果表明,该方法实现了对不同直径(0.32,0.4,0.6 mm)和宽度(0.05,0.08,0.1mm)环形焦斑的整形,可有效应用于激光束整形。     

基于ANSYS的圆形压电振子的仿真分析与研究

利用ANSYS软件建立了压电振子的有限元模型,对圆形压电振子的基板和压电陶瓷片的材料参数、结构参数对其变形的影响进行了分析和对比,根据仿真结果,确定了作为泵腔动力元件的圆形压电振子的参数。对选定的圆形压电振子进行了静态特性、阻抗特性和幅频特性的实验测试,研究了不同波形、不同电压、不同频率驱动信号对振子变形的影响。通过对比实验测试结果和有限元仿真结果,验证了有限元模型的可靠性,为优化压电晶片驱动器结构参数提供了有效的方法。     

平面子孔径拼接测量实验研究

通过椭圆形口径（长轴225mm,短轴161mm）SiC平面反射镜的全口径面形测量加工实验,验证了一种新的子孔径拼接测量算法—子孔径拼接迭代算法（SASL算法）的有效性。首先用100mm口径平面平晶的子孔径拼接测量与全口径测量的对比实验,确定了拼接测量相关参数及测量装置的精度指标。在此基础上设计了SiC平面反射镜的子孔径拼接实验,在搭建的拼接装置上实现了五次离子束迭代加工过程中和最终的全口径面形测量。这是国内首次将子孔径拼接测量方法用于指导加工实践,加工过程中的测量结果为面形误差修正提供了准确的数据,保证了最终全口径面形误差快速收敛到RMS 50nm。实验证明,SASL算法能大大放宽拼接装置对准运动的精度要求,并减少拼接过程对拼接结果的影响。     

Dynamic response of ferrofluidic deformable mirrors using elastomer membrane and overdrive techniques

The experimental results obtained with a ferrofluidic deformable mirror controlled by electro-magnet actuators are presented here. Using a step input through a single actuator, we obtained a steady-state settling time of 100?ms; however, different combinations of overdrive inputs can be used to decrease it to 25?ms. A new technique which consists of laying down an elastomer membrane, coated with an aluminum film, on the ferrofluid is also discussed. By adding the membrane on the ferrofluid, it further decreases the time response by a factor of 2. Furthermore, the thin aluminum layer improves the reflectivity of the mirror. Finally, using the membrane and the overdrive techniques combined, the time response is improved by a factor of 20. Numerical simulations show that ferrofluidic mirrors using membranes and improved electronics should reach settling times of the order of a millisecond. Presumably, even lower settling times could be possible.     

高能激光反射镜热变形补偿

研制了一套由压电陶瓷驱动器、压力传感器、环状力施加机构和控制电路组成的反射镜动态热变形补偿系统用于补偿激光反射镜热变形球差。圆形反射镜在两个同轴不同半径的环形力作用下,其内环区域产生曲率可变的抛物面形变,由此补偿反射镜热变形带来的球差项。对镜体进行了有限元数值计算,建立了变形量与沉积热量与受力的关系。采用口径为100mm,厚度为8mm平面反射镜进行了受力-变形以及辐照-受力-变形实验,利用干涉仪对面型进行监测。研究表明,在不同推力作用下,有效区域内变形始终保持抛物面形。给出了推力-面型变化曲线,在225N推力下,中心最大变形超过3μm。在不同热沉积量下,镜体中心位移和受力保持线性关系,力-变形系数为0.013μm/N。     

压电悬臂梁发电装置的建模与仿真分析

为提高一定尺度压电复合悬臂梁（简称压电梁）的发电能力,建立了单、双晶压电梁发电能力的仿真分析模型,研究了结构尺寸、激励方式及材料性能等对其发电能力的影响规律。研究表明,在基板材料及激励条件相同时,存在不同的最佳厚度比使单／双晶压电梁发电能力最大,双晶梁的最大发电量约为单晶梁的2倍。基板材料不同时,最佳厚度比随（基板与压电材料的）杨氏模量比的增加而减小,铝、钼基板构成的单／双晶压电梁的最佳厚度比分别为（0.7,0.32）和（0.45,0.2）。在相同的厚度比（0.5）及外界激励条件下,杨氏模量比对两种电梁发电能力的影响不同,杨氏模量低于3.3时,双晶梁的发电量均大于单晶梁。     

可动态应用的压电陶瓷驱动电路的实验研究

对已有的PZT(压电陶瓷)驱动电路进行分析和改进,设计并完成了一个具有良好动态特性的PZT驱动电路。实验结果表明,对于多种不同的信号波形,此驱动电路都可以实时、线性、几乎无失真地将输入信号放大到驱动PZT所需的电压。利用正弦波作为输入信号时,测出了此驱动电路的频率响应范围。此外,发现当输入信号频率发生变化时,驱动电路消耗的功率也相应发生变化,经过作图分析可以得出驱动电路消耗的功率与输入信号频率是成线性关系。在文献中尚未见到研究PZT驱动电路消耗功率与输入信号频率相关性的报道。     

基于PI迟滞模型的单压电变形镜开环控制

压电非线性迟滞导致压电变形镜的开环控制精度及闭环工作带宽降低,限制了其在自适应光学系统中的应用。为克服迟滞影响,提出采用PI迟滞模型描述单压电变形镜的迟滞非线性特性,实现单压电变形镜的高精度开环控制。首先建立PI迟滞数学模型,利用最小二乘法辨识PI迟滞模型的权值,计算出PI逆模型的权值和阈值,从而获得消除迟滞后的变形镜控制电压;接着搭建了基于哈特曼波前传感器的自适应光学测试平台,采用单压电变形镜的环形致动器进行离焦面形的开环控制实验。实验结果表明,经过迟滞消除后变形镜的电压-变形迟滞由9.3%降低到1.2%,离焦面形的开环重构精度提高70%以上,证明该迟滞模型可有效应用于单压电变形镜的开环控制。     

Nonlinear free and forced vibration of simply supported shear deformable laminated plates with piezoelectric actuators

This paper deals with the nonlinear vibration and dynamic response of simply supported shear deformable cross-ply laminated plates with piezoelectric actuators subjected to mechanical, electrical and thermal loads. The material properties are assumed to be independent of the temperature and electric field. Theoretical formulations are based on the higher order shear deformation plate theory and general von Kármán-type equation, which includes thermo-piezoelectric effects. Due to the bending and stretching coupling effects, a nonlinear static problem is first solved to determine the pre-vibration deformation caused by temperature field and control voltage. By adding an incremental dynamic state to the pre-vibration state, the equations of motion are solved by an improved perturbation technique to determine nonlinear frequencies and dynamic responses of hybrid laminated plates. The numerical illustrations concern nonlinear vibration characteristics of unsymmetric cross-ply laminated plates. The results presented show the effects of temperature rise, applied voltage and stacking sequence on the nonlinear vibration and dynamic response of the plates.     

Experimental study of neutron induced background noise on gated x-ray framing cameras

A temporally gated x-ray framing camera based on a proximity focus microchannel plate is one of the most important diagnostic tools of inertial confinement fusion experiments. However, fusion neutrons produced in imploded capsules interact with structures surrounding the camera and produce background to x-ray signals. To understand the mechanisms of this neutron induced background, we tested several gated x-ray cameras in the presence of 14 MeV neutrons produced at the Omega laser facility. Differences between background levels observed with photographic film readout and charge-coupled-device readout have been studied.     

纵弯超声电机压电振子的动力学数值模拟

利用压电陶瓷的本构方程和弹性动力学方程建立了压电驱动问题机电耦合场的有限元模型,基于有限元程序自动生成平台FEPG,通过编写元件化程序,得到此类结构的有限元计算程序.对纵弯超声电机压电振子的动力学特性进行了分析,结果表明该程序可以用于压电驱动类结构的的动力学数值计算.     

纳米精度压电马达的动力学模拟及试验

设计并制作完成了一种基于压电陶瓷逆压电效应的纳米精度压电步进马达.根据其结构简化模型,推导出该压电纳米马达在脉冲电源作用下的运动特性表达式.编写软件,设定参数对压电马达的运动性能进行模拟,结果表明了马达的线性步进运动特点.设计光栅测试系统,对压电马达样机进行运动测试,试验结果证实了模拟结构的正确性.该类压电纳米马达具有可以实现连续步进位移,步进速度快,单步分辨率小,行程长和便于利用微机实现智能控制等特点.纳米马达的位移分辨率可以达到10nm,最快速度为0.6mm/s,最长行程为5cm.     

应用在拼接镜面中的电容位移传感器的结构性误差分析及校正

分析了子镜运动和电容传感器极板运动之间的理论关系并探讨了电容位移传感器读数的"结构性"误差的处理方法。基于电容位移传感器的工作原理,对极板为圆形的电容位移传感器提出了采用以位移的测量值和子镜转角为自变量的多项式拟合的校正方法。计算表明该误差处理和校正方法是简洁可行的。对于转角的拟合只需2阶,同时位移测量值只需4阶的多项式进行拟合即可使输出位移达到3 nm的精度。进一步分析表明,直接使用位移传感器读数计算极板转角,并对误差的主动校正控制非常有利于该多项式拟合,可一次性达到优于5 nm的校正误差,完全满足拼接镜面主动光学工程应用的技术要求。     

Computer simulation of a piezoelectric angular rate sensor

The paper presents the finite element (FE) modeling of operation of a rotational motion sensor that uses a balanced oscillator (tuning fork) to sense the angular rate. The 3D FE model has been employed for the investigation of the dynamic properties of the sensor. The sensitivity functions have been obtained for adjusting the geometric parameters of the quartz element in order to achieve the desired values of natural frequencies. The performance of dynamic computations has been improved by truncating the dynamic contributions of higher modes of the vibrating structure.

Results are presented in terms of performance characteristics of the sensor against the design parameters in various modes of operation.     

变形镜面形影响函数的有限元仿真

在自适应光学系统仿真分析中,变形镜的面形影响函数通常采用高斯函数近似,由于实际变形镜受驱动器排布影响,其面形影响函数与高斯函数存在出入,以致用高斯函数拟合波面时带来高阶像差。文中利用有限元方法,仿真变形镜的面形影响函数,并与高斯函数进行了比较,证明所建立的变形镜有限元模型能更实际地反映变形镜的波面校正能力。     

小形变变形镜的设计及其在低像差脉冲压缩光栅中的应用

考虑激光脉冲啁啾放大与压缩技术要求脉冲压缩光栅有较低的像差,设计并制作了一个小形变变形镜来补偿大口径光栅基板加工残余的亚微米级静态像差对光栅波像差的影响。该变形镜有效口径为80mm、厚度为5mm,包含19个分立式压电促动器。采用干涉仪测量得到各个促动器的响应函数,构建了变形镜的刚度矩阵;采用最小二乘法求解出获得目标面形时各个促动器上所需施加的控制电压;通过整体优化和局部优化的结合,使变形镜的目标面形得到了有效控制。应用该变形镜构建了主动式全息光学记录系统,并选用具有较大像差的基板开展了光栅像差补偿实验。实验显示,对残余像差为~0.93λ的基板,采用变形镜后制作出了残余波面PV可达0.14λ(@633nm)的脉冲压缩光栅,验证了小形变变形镜在光栅基底像差补偿上的有效性。     

Experimental study on elastic deformation machining process for aspheric surface glass

Elastic deformation machining is a fabrication method that exploits the elastic deformation properties of materials under stress. Coupled with plane lapping machining process, this new fabrication method is suitable for machining complex aspheric surfaces. Upon completion of the machining process, the workpiece under process will be shaped into a desired surface form. The elastic deformation machining has several advantages over traditional fabrication methods, i.e., high machining compatibility and high fidelity of material property during machining process. The subject of this study is to determine the surface shape of the finished glass workpiece after the lapping process of the elastic deformation machining. The experimental results were compared with theoretical calculations. In the case when the vacuum pressure is 50 kPa, the maximum deviation value between the deformation curves from the theoretical calculation and the experiment results is within 62 μm. In order to improve the precision of form surface, the vacuum pressure is modified from 50 to 42 kPa. This reduction corresponds to a change of workpiece thickness when it is lapped. The results of the change of vacuum pressure show that the form accuracy produced is improved significantly and agrees very well with theoretical calculations. The maximum deviation in this case is 1.6 μm. The study indicates that the experimental plane lapping setup that exploits the material elasticity property can be utilized to fabricate aspheric lenses with axisymmetric surface and low complexity.     

无阀压电泵的流固耦合仿真及试验验证

提出利用结构分析软件ANSYS和流体分析软件ANSYS CFX对无阀压电泵进行流固耦合仿真分析,以研究无阀压电泵的输出性能。分别对进口在中间出口在一侧、出口在中间进口在一侧、进出口对称布置的3种不同结构形式的无阀压电泵进行了流固耦合仿真分析。结果显示,上述3种无阀压电泵中,出口在中间进口在一侧结构形式的无阀压电泵的宏观输出流量最大。制作了3种无阀压电泵的试验样机,并搭建了相应的试验测试系统,在幅值为45 V、频率为0~700Hz的正弦信号激励下对其输出流量进行了测试。结果表明,3种不同结构形式的无阀压电泵的最大输出流量分别为3.8、6.0和4.0ml/min,出口在中间进口在一侧的压电泵输出流量最大,与流固耦合仿真分析的结果相吻合,验证了本文提出的流固耦合仿真分析的方法可以指导压电泵的设计。