双层介电薄膜结构双液体变焦透镜的研究

在双层介电薄膜结构双液体变焦透镜模型的基础上,分析了透镜焦距与外加电压、双层介电薄膜的介电常量、薄膜厚度等参量的关系.并以降低双液体变焦透镜驱动电压为目的,选择了相对介电常量较高的五氧化二钽薄膜作为内层介电层,相对介电常量较低的防水层为外层介电层,分析了双层介电薄膜的厚度以及厚度的匹配对双液体变焦透镜的变焦范围和驱动电压的影响,在保证一定的变焦范围并尽可能降低透镜驱动电压情况下获得最佳透镜工艺参量.模拟结果表明:疏水层薄膜厚度比高介电层薄膜厚度小很多时,双液体变焦透镜可实现低压驱动,且双液体变焦透镜在一定变焦范围内所需驱动电压可下降到10V以下,而疏水层薄膜厚度与高介电层薄膜厚度相当或高于高介电层薄膜厚度都不能有效利用高介电薄膜的高介电性能来降低双液体变焦透镜的驱动电压.     

双液体变焦透镜变焦迟滞现象的研究

通过引入接触线摩擦力,建立了基于双液体变焦透镜内壁的液液固三相系统接触线的力学物理模型,重新对非理想状态下液液固三相系统接触线进行了受力分析.在此基础上,对杨氏方程进行了改进,合理地解释了双液体变焦透镜的变焦迟滞现象.通过对疏水介电层厚度为2 μm的双液体变焦透镜进行加电压变焦实验,给出了双液体透镜的焦距与电压之间的迟...     

介电弹性体驱动液体透镜的设计与分析

介电弹性体具有结构紧凑、形变量大、响应速度快及易集成等特点,为了降低驱动电压,将介电弹性体应用于液体透镜中,采用介电弹性体和透镜薄膜分离结构,建立了介电弹性体主动薄膜变形、透镜薄膜变形以及液体透镜焦距的数学模型。仿真结果表明,当初始液体压力为500 Pa、驱动电压为1000 V时,液体透镜的变焦范围为15.13～22.80 mm,焦距增加了为51%。分析了介电弹性体的杨氏模量、残余应力、初始厚度及半径对液体透镜焦距的影响,结果表明,同等增加倍率下,介电弹性体的初始厚度对液体透镜焦距的影响最大,其次为残余应力,该研究结果可为优化设计介电弹性体驱动的液体透镜提供参考。     

含有圆孔平板电极结构的双凸液体透镜的设计与分析

基于平行平板电极的变焦液体透镜的有关研究,通过应用介电泳效应,提出了一种含有圆孔平板电极结构的双凸液体透镜模型,是一种新型的三层液体透镜结构.利用Comsol,Matlab和Zemax软件仿真分析了该模型在不同电压下的面型变化与成像光路,得出其变焦范围为22.6—15.9 mm,并对制备的器件进行具体的实验分析,获得了不同电压下双凸液体透镜的液滴上下界面面型和该透镜的变焦范围23.8—17.5 mm,与仿真结果基本一致,而且其成像分辨率可达到45.255 lp/mm.结果表明,所提出的这种新型三层液体结构的双凸液体透镜具有结构简单、易于实现的特点,而且具备良好的成像质量.     

基于电湿效应的双液体透镜

介绍了一种新型的、基于电湿效应的双液体透镜的发展历史、结构原理,通过改变外加电压的大小以调节透镜的焦距,从而达到无机械运动变焦的目的.推导并分析了两种液体透镜模型的焦距与外加电压的关系.     

柔性变焦透镜发展现状

本文从基于力致变形(机械传动)驱动和基于电致变形(智能材料)驱动两方面分析了柔性变焦透镜(FVFL)的发展现状。通过归纳和分析发现:柔性变焦透镜均存在温度、重力对稳定性的影响。传统力致变形驱动的柔性变焦透镜变焦范围大,但响应速度慢,不易微型化设计;电致变形驱动的柔性变焦透镜响应速度快、结构紧凑。改善变焦透镜成像质量、降低驱动电压是目前柔性变焦透镜的研究热点。探索新颖的驱动方式,研究低功耗、智能化变焦系统将是柔性变焦透镜的主要发展趋势。     

基于介电润湿三液体透镜的变焦光学系统的设计与分析

提出了一种基于介电润湿效应的三液体透镜与传统固定透镜组合的三组元结构变焦光学系统.在一、三组元固定不变的情况下,通过移动中间三液体透镜组改变系统焦距,并通过三液体透镜的自变焦特性,确保系统在变焦的同时保持像面位置不变.采用光焦度高斯括号法求解系统的初始结构参量,利用Zemax光学软件进行系统设计与优化,最后对系统的成像质量进行分析.结果表明:该系统总长22mm,可实现2.7~20.3mm范围内的连续变焦,系统变倍比接近8,在空间频率180lp/mm处调制传递函数值均大于0.4.     

基于金属侧壁结构的电润湿液体透镜

金属具有良好的可加工性和导电性,利用金属制作液体透镜的壁垒,可有效地提高基于介质上电润湿液体透镜的抗震抗摔、耐电压,以及侧壁电极可加工等性能。针对材料表面平整度对击穿电压的影响进行了相关的研究,在此基础上制备的液体透镜聚焦性能良好,焦距变化的理论值与实验测量值高度吻合,可实现3cm至无穷远范围内的有效变焦。基于金属侧壁结构的电润湿液体透镜将在柔性显示以及液体透镜阵列化、多型化发展中发挥重要的作用。     

电湿效应变焦光学系统的设计与分析

与传统的通过电机调节透镜相对位置达到变焦目的设计完全不同,提出了一种设计无机械运动变焦光学系统的新方法.利用亥姆霍兹自由能最小化方法推导出适合双液体变焦透镜的杨氏方程,将以气液固三相系统为基础的传统杨式方程扩展到了液液固三相系统.以圆柱结构的双液体变焦透镜为组分设计了一种新型的变焦光学系统,分析了系统在外加电压作用下使焦距变化的同时又能保持像面不变时必须满足的条件.模拟结果表明该系统的变倍比大约可达到1:1.5.     

大变倍比液体透镜变焦系统设计

分析了电润湿液体变焦透镜的光学特性和变焦系统设计理论,将各组元焦距作为变量,列出了该液体透镜变焦系统的变焦方程.利用粒子群算法优化求解变焦方程,得到符合条件的初始结构;再利用优化设计软件进行像差平衡,设计了一个具有4片液体透镜,焦距为20~120mm的大变倍比液体透镜变焦系统.系统各焦距处光学传递函数在66lp/mm处均大于0.3,畸变小于2%,满足设计要求.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.