掺杂分散红73的有机聚合物PMMA薄膜全光极化的研究

制备了以分散红73为客体的PMMA掺杂型有机聚合物薄膜样品,对之进行了全光极化特性的研究,极化使薄膜产生二阶非线性,种子光的强度越大,其二阶非线性极化率达到饱和值越快;种子光的位相差、相对强度比、光场强度比等因素影响薄膜的二阶非线性的优劣。     

ZnO薄膜非线性光学特性的实验研究

利用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上生长一层高质量的ZnO薄膜。为了考察沉积温度对样品的非线性特性的影响,在200~500 ℃生长了一系列ZnO薄膜。用X射线衍射谱(XRD)及扫描电镜(SEM)对样品结构进行了评价。以Nd:YAG激光器输出的1.06 μm的激光为基频光,对ZnO薄膜样品的二阶及三阶非线性光学特性进行了实验研究。实验发现,对于250 ℃沉积温度的样品有较强的非线性效应,实验测得的二阶非线性极化张量 χ ⁽²⁾_ZZZ=9.2 pm/V, 三阶有效非线性系数χ⁽³⁾=5.28×10^－20 m²/V²。     

非线性光学聚合物电光活性稳定性的快速老化模型实验

利用旋涂法制取了掺杂型非线性光学聚喹啉材料的高分子材料薄膜,并用平板电场极化法对NLO聚喹啉材料的高分子材料薄膜进行了极化.然后,利用锁相放大器测量并给出了该高分子材料的线性电光系数(r33)衰减曲线,唯象地引人双指数衰减模型的常数项,并据此模型得到了新的拟合曲线.提出了永久线性电光系数r33 (∞)系数和稳定性比ξ的...     

铁电存储器薄膜的计算机模拟

随着信息技术的迅速发展,对信息存储器提出了以下要求高密度、高读写速度、低功耗和尽可能长的存储寿命.铁电薄膜材料在存储技术中的应用出现为这一切提供了可能.本文在分析铁电材料自发极化机制的基础上,建立了铁电薄膜的微观极化模型,通过计算铁电系统中的能量和有效电场,根据铁电极化的运动方程,模拟出铁电薄膜的电滞回线,为铁电薄膜材料的信息存储提供理论指导.     

0.1 HoMnO3-0.9BiFeO3柔性铁电薄膜的制备及电学性能

采用脉冲激光沉积技术在云母柔性衬底上沉积0.1HoMnO_3-0.9BiFeO_3薄膜,研究了薄膜的晶体结构、表面形貌、弯曲服役特性、铁电和介电性能以及输运特性。结果表明:BiFeO_3沿(012)和(104)晶面取向生长,结晶良好;薄膜表面光滑,均方根表面粗糙度为6.7nm,连续弯曲平整10 000次后表面无细微裂纹;薄膜具有良好的微观压电性,且呈现出一定的向上自发极化特性;薄膜的饱和极化强度和剩余极化强度分别为68,61μC·cm~(-2),弯曲至曲率半径为2.2mm时的极化强度变化不大,连续弯曲平整10 000次后则有所降低,平整状态和弯曲状态下的介电性能相差较小;薄膜的激活能为0.42eV,低于纯BiFeO_3薄膜的,其载流子输运能力有所增强。     

BBO晶体中的级联二阶过程和三阶光学非线性效应

本文讨论了非线性光学晶体中的级联二阶过程。在小信号转换近似下,这一过程被公式化,由三阶非线性极化率表示。作为比较,用自位相调制和光学混频方法,研究了BBO晶体的级联二阶过程。发现由于这一过程的存在,该晶体的三阶非线性被明显增加,极化率达10^-19m²/V².     

电晕极化智能程控系统

为非线性聚合物电光材料及调制器项目,研究开发了电晕极化智能系统.系统对使用的商品化电源、温度控制器作了相应的改造,研制了接口电路,用四次多项式校正输入/输出信号的非线性,用VB的时间控件设计极化时间控制程序,用基于面向事件的VB开发软件,设计了可视化界面,以电子表格方式设置、增删实验参数,以表格、图形方式显示、存档、再现、打印实验数据.实现了电晕极化时间、温度和高电场的全自动实时控制.     

碳纳米管改性压电薄膜极化工艺的研究

合理的极化工艺是保证0-3型压电复合薄膜良好压电性的重要条件,而影响压电薄膜极化效果的因素很多,其中主要因素是极化电场E、极化温度T和极化时间t。为了改进压电薄膜的电学性能,制备了碳纳米管改性的压电复合薄膜,并采用自制的极化夹具,在硅油中对压电薄膜进行极化,通过分析极化电压、极化温度、极化时间对压电复合薄膜压电应变常数的影响及不同极化条件下压电应变常数随时间的退化状况,进一步优化了压电复合薄膜的极化工艺,提高了压电复合薄膜的压电性能。     

用作驻极体话筒储电层的ETFE薄膜的电荷储存

利用表面电位衰减测量和热刺激放电电流谱(TSD)分析,研究了乙稀/四氟乙烯共聚物ETFE驻极体中的沉积电荷稳定性及其与极化条件的关系.结果显示,ETFE薄膜驻极体具有优良的电荷储存稳定性,而且其沉积电荷稳定性与极化方式有关.组合ETFE突出的力学性能,使其有望作为驻极体声传感器的储电振膜.     

电晕极化的铁电聚合物驻极体极化强度的估算

本文首次根据栅控恒压电晕充电组合反极性电晕补偿充电法的实验结果计算出电晕极化的PVDF铁电聚合物驻极体的极化强度.实验结果说明PVDF铁电聚合物驻极体在180MV/m极化电场下可能形成约35mC/m2的高极化强度.电晕充电组合反极性电晕补偿充电法是研究极性驻极体材料电极化的一种有效方法.     

Multibeam laser writing of diffractive optical elements

A new version of the method of direct multibeam laser writing of diffractive optical elements (DOE) is proposed and investigated. A writing area in the form of an array of focused light spots is formed by splitting the writing laser beam into multiple beams by using a Dammann grating and focusing of these beams in the plane of a moving carrier with a photosensitive material. Adjustment of the radial pitch of writing and correction of the uniformity of the beam intensity is carried out by tilting the Dammann grating and displacing it in the dispersion direction. In writing DOEs, the radial pitch of discrete displacement of the writing area with respect to the plane of the DOE is set equal to or multiple of the average radial distance between the radial projections of the centers of the focused light spots. This version provides improved performance and accuracy due to high-quality paralleling of the writing beam and the averaging effect in superimposed writing.     

Fibre‐optical microendoscopy

Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high‐quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro‐scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one‐photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two‐photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre‐optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner.     

基于拉盖尔-高斯光束的螺旋干涉模式研究

为提高粒子操控的灵活性和精度,一种基于拉盖尔-高斯光束的可控螺旋干涉模式被提出。通过理论分析两束拉盖尔-高斯光束同轴叠加光场,给出了不同参数的变化对干涉光场强度分布的影响。通过仿真模拟,研究参数变化对场强结构的调控作用。结果表明,通过改变两束拉盖尔-高斯光束的拓扑电荷数可以实现干涉模式光场强度极大值的数量和分布的动态调整,增加了对粒子操控的灵活性和可控性,为提高光束微粒操控的精度的提升提供了可能。     

Simple positioner with nanometer reproducibility of the focused light beam position on an object

A simple positioner, which allows one to ensure the position of a focused light beam on an object with nanometer precision and reproducibility, is proposed and studied. It can be used for positioning of focused beams (in particular, laser beams) on surfaces of optical fibers, biological objects, optical disks, thin film modulators, and holographic memory systems in the micrometer and nanometer ranges.     

激光聚变冲击波被动式测速光学系统设计

针对激光聚变装置冲击波速度被动测量的需求,设计了一种测速光学系统。采用高紫外透过率的氟化玻璃,实现了透射式300～800nm复消色差设计。系统光路具有前后两组镜头,中间为平行光,镜头间距可变,光路适应能力强。系统前端两侧的双目机器视觉能够完成自动寻的。平行光路中设置5个激光器,轴上的1个前向照明靶点用来观察条纹相机狭缝处的目标像质,轴外的4个与光轴平行后向传输用来标识系统光轴的位置,激光器部件可电动切入/切出。系统前组镜头F/#数为4,宽谱工作物方分辨率优于10μm,532nm单波长工作物方分辨优于5μm。该光学系统光路排布灵活,可单独被动测速,也可与主动测速系统VISAR耦合构成主被一体复合测速系统,满足激光聚变装置冲击波测速的需求。     

关于分振幅等倾双光束干涉条纹反衬度的讨论

为讨论单色平面光经过透明平行平板后出现的两束主要反射光之间干涉条纹的反衬度,在给出了它们的光矢量方位角的定义之后,利用方位角之差表示出两束光波光矢量之间的夹角;再利用菲涅耳公式表示出两束光波的光强比,从平面波干涉的角度来求两束光之间干涉条纹的反衬度,最终得出了复杂而普遍的表达式。并针对海定格干涉的反衬度进行了讨论,认为小角度入射形成的海定格干涉条纹,其反衬度只决定于平行平板的折射率;利用光学材料制作的平行平板,其海定格干涉条纹具有很高的反衬度。     

分块非线性加权在车灯检测仪校准器光轴角测量中的应用

针对传统光轴角测量系统中人为因素干扰导致的重复性能降低等不足,设计一种基于图像处理技术与高精度电控转台相结合的自动测量方案。分析了照明光斑光强分布特性,提出了一种基于图像区域分割的最优非线性加权的特征点提取算法。该方法根据光强与灰度的线性关系,将光强量化到3个区间。然后分析灰度因素在特征点定位中的影响;针对不同区间应用局部最优加权法则以实现局部最优化处理。最后,利用光轴偏转角与特征点在像面上位移的对应关系,计算得到光轴角测量值。开展了光斑特征点重复性实验并分析了光轴角检测精度,结果表明:该系统在不同光强、不同角度条件下重复性好,测角精度优于60.18″。与激光光源的光轴角测量实验对比,该算法在光斑光强分布不均的条件下仍能完成稳定且精确的光轴角测量。     

受控等效光速减缓及其在磁场强度测量中的应用

提出一种基于等效光速减缓的光纤磁场强度传感方法,可用于细长型沿轴线呈线性分布的线圈的场强测量。工作时,多束激光可在光折变光纤内写入固定和移动两种光栅。将光纤置于特定磁场中,磁光效应导致部分光栅失效,从而改变了光速的等效减缓量。实测减缓量即可间接测得磁场强度值。     

Monochromatic image analysis of elastohydrodynamic lubrication film thickness by fringe intensity computation

Point contact film thickness in elastohydrodynamic lubrication (EHL) is analyzed by image processing method for the images from an optical interferometer with monochromatic incident light. Interference between the reflected lights both on half mirrorCr coating of glass disk and on super finished ball makes circular fringes depending on the contact conditions such as sliding velocity, applied load, viscosity-pressure characteristics and viscosity of lubricant under ambient pressure. In this situation the film thickness is regarded as the difference of optical paths between those reflected lights, which make dark and bright fringes with monochromatic incident light. The film thickness is computed by numbering the dark and bright fringe orders and the intensity (gray scale image) in each fringe regime is mapped to the corresponding film thickness. In this work, we developed a measuring technique for EHL film thickness by dividing the image patterns into two typical types under the condition of monochromatic incident light. During the image processing, the captured image is converted into digitally formatted data over the contact area without any loss of the image information of interferogram and it is also interpreted with consistency regardless of the observer’ s experimental experience. It is expected that the developed image processing method will provide a valuable basis to develop the image processing technique for color fringes, which is generally used for the measurement of relatively thin films in higher resolution.