以氧化铅作反射镜基底能提高反射率

苏修科学工作者宣称,用氧化铅作基底的电介质反射镜优于通常用的以ZnS作基底的镜子。他们的看法基于这样一个事实,即制备时所需的真空度不需要很高,因此,氧化铅能在比较低的温度下蒸发。对大量用氧化铅和冰晶石作的具有各种层数的反射镜在不同光谱区进行试验,结果表明,它们比用ZnS作成的反射镜有更髙的反射率。发现这些反射镜特别适用于10焦耳数量级的低输出能量激光器。     

车载大口径FSM用SiC反射镜制备工艺研究

为了获得高面形精度、高反射率的轻质反射镜,选用SiC为基底材料,对反射镜的加工制备工艺进行了深入研究。首先从车载大口径FSM中平面反射镜的应用需求出发,提出了反射镜的主要设计指标。然后,针对反射镜的轻量化结构采用反应烧结法获得镜坯,并通过机械加工使其接近成型;继而采用物理气相沉积法对SiC反射镜进行表面改性处理,进而采用古典抛光法对反射镜进行光学精加工;最后在反射镜的工作表面镀覆金反射膜。在完成车载大口径FSM用SiC反射镜的加工制备后,对反射镜的面形精度和反射率进行了实验检测。结果显示:SiC反射镜的面形精度(RMS值)优于λ/30;对中波激光的反射率约为98.0%,对长波激光的反射率约为98.2%;均满足车载大口径FSM的应用需求。     

利用平滑层减小极紫外多层膜基底粗糙度的方法

在极紫外多层膜反射镜中,基底高频粗糙度是影响多层膜反射率的重要因素.通过在粗糙基底上镀制平滑层薄膜,可以有效降低基底粗糙度.叙述了平滑层减小多层膜基底粗糙度的原理,研究了不同镀膜工艺条件下平滑层对基底粗糙度减小效果的影响.结果表明,当工艺参数选择合适时,在粗糙基底上镀制平滑层,可以减小基底粗糙度.     

铝合金反射镜

在反射镜材料选择方面，不管是用于空间的低温环境还是战术坦克的强冲击条件，都必须注意寻找性能大大优于常规反射镜的基底。尽管材料供应商尽力研制特殊反射镜用的陶瓷和金属基底，但都没有关于材料特性、效能和成本的信息。这一领域的一个例外是ARCO化学公司先进材料部，正在使一种特殊类型的工程金属基质化合物商品化。     

红外大功率CO2激光器高反射金膜的镀制

本文报导了大功率CO2激光器高反射金膜的制作方法，介绍了较为理想的基底材料——青铜，和青铜为基底材科的镀金膜作为高能激光器的光学谐振腔的全反射膜以及作为改变光路的反射镜的使用情况。在激光分离同位素的实际使用中，效果良好。     

作红外激光应用的优质多层減射膜

一般说来,作红外应用的大多数高反射率激光反射镜,目前是用蒸汽淀积技术将多层膜淀积在牢固的和相当昂贵的基底材料(如锗、硅及红外材料)上而制成的。尽管用这种技术能获得高反射率的反射镜,但往往出现一些问题,例如产品少和易脆等等。     

单驱动变曲率单晶硅反射镜的研究

为了解决高能激光器输出光束的光束质量随时间蜕变的问题,提出了一种主动光学元件的结构,只使用一个驱动器使反射镜的曲率产生可控制的改变,用以补偿高能激光器中增益介质或光学元件因热效应而产生的球差。通过理论模拟计算和实验研究对比验证,这种结构能够使单晶硅基底的反射镜产生微小变形,通过精确控制驱动器,可以使反射镜产生所需要的曲率变化。结果表明,这种主动光学元件可以用于谐振腔内补偿高能激光器中热效应产生的球差项的影响。     

压电薄膜自适应变形微反射镜阵列研究

介绍了自适应光学系统中的一种全新的基于Pb（ZrxTi1-xO3）（PZT）薄膜的微反射镜阵列。通过控制PZT薄膜两端电压实现微镜单元的微量形变,改变反射镜局部面形,校正畸变波面的波差,改善成像质量。该方案在重掺杂Si片基底上依次制备PbTiO3（PT）、PZT,最后镀Al作为反射面,形成Si／Pr／PZT／Al的膜层结构。对制备完全的试片在数字波面干涉仪上进行了形变测试,尽管受到了薄膜热形变作用的影响,仍实现了约1．2μm的可控形变,证明该方案用做自适应变形反射镜的可行性。     

波长为1.03nm的掠入射多层膜反射镜的设计

在软x射线短波段1.03nm处的掠入射多层膜反射镜的设计中，本文提出了一种理论设计的修改方法。该方法考虑了基底，膜层界面间的均方根粗糙度与反射率的影响，对界面的数学描述源于D.G.Sterns的散射理论。设计结果表明：要在1.03nm处制做较高反射率（10%）的掠入射多层膜反射镜，基底粗糙度小于0.56nm即可，使用超精加工的粗糙度为0.5nm的基片作为基底，沉积了多层膜反射镜后，其反射率结果是10%，与修改方法结果一致。     

光学扫描:快速扫描应用驱动反射镜设计

1 引言 成功的扫描需要将反射镜、镜座和电机集成于"M立方(M Cubed)"系统中.应用于扫描的反射镜必须具备低惯性,同时满足动态平面度和充分散热的要求.快速扫描意味着激光光束要有较宽的带宽,这就需要整个扫描系统具有抗扰性.而反射镜基底材料、电机和电机连接装置、最小惯性结构、散热设计和激光损伤阈值等因素也会影响集成的最终效果.因此,设计者必须权衡考虑材料、机械装置和各种扫描参数,才能使系统发挥最佳工作性能.     

应用于OTDR测试的光纤光栅反射器

本文阐述了反射器在PON的OTDR测试诊断系统中的作用及其必要性,探讨了光纤光栅反射器方案的应用特点、与介质薄膜滤波器对比的优势及在国际市场上的应用情况,并介绍了目前光纤光栅反射器在成本方面的突破。     

高耐温精密冷反光镜研制

高耐温精密冷反光镜是应用于影像光学系统的一种常用光学元件,它具有高耐温性、反射可见光、透射红外光的特点。本文介绍了采用低膨胀系数的高耐温性基底材料,利用电子束热蒸发物理气相沉积镀膜方法及离子辅助沉积工艺,制备出了可见光光谱平均反射率高于95%、红外光光谱平均透过率高于85%,膜层耐温性能达到450℃高温下膜层无异常的反光镜产品,并实现了批量生产。     

Cross polarizing effects of a water film on a parabolic reflector at microwave frequencies

The cross polarizing effects introduced by a uniform water film on the surface of a parabolic reflector are evaluated at 10 and 34 GHz. The reflector is considered to be illuminated by an isotropic linearly polarized source at the focus, but the analysis can be applied for any given primary feed aperture field distribution. The aperture cress polarized field is obtained, and a worst case diffraction field (when opposite quadrants of the reflector are wet) is then calculated. A relatively low level cross polarizing effect is predicted, dependent on diameter-to-focal-length ratio.     

单晶LN BAW谐振器有限元仿真研究

利用离子注入剥离法(CIS)制备的铌酸锂(LN)压电薄膜可用于制备体声波(BAW)器件,近年来备受关注。滤波器的指标与谐振器的性能密切相关,但基于LN单晶薄膜的BAW谐振器,对其结构的仿真优化还未有较深入的报道。该文以LN单晶薄膜为核心压电层材料,构建了固态反射型(SMR)单晶薄膜谐振器有限元仿真模型,对其压电层厚度和布喇格反射层厚度进行了设计,并重点针对谐振器上电极的台阶结构进行了二维模型仿真,为高频LN BAW滤波器的制备提供了理论依据。     

Simulation and implementation of a porous silicon reflector for epitaxial silicon solar cells

One of the main challenges in the ongoing development of thin film crystalline silicon solar cells on a supporting silicon substrate is the implementation of a long‐wavelength reflector at the interface between the epitaxial layer and the substrate. IMEC has developed such a reflector based on electrochemical anodization of silicon to create a multi‐layer porous silicon stack with alternating high and low porosity layers. This innovation results in a 1–2% absolute increase in efficiency for screenprinted epitaxial cells with a record of 13·8%. To reach a better understanding of the reflector and to aid in its continued optimization, several extensive optical simulations have been performed using an in‐house‐developed optical software programme. This software is written as a Microsoft Excel workbook to make use of its user‐friendliness and modular structure. It can handle up to 15 individual dielectric layers and is used to determine the influence of the number and the sequence of the layers on the internal reflection. A sensitivity analysis is also presented. A study of the angle at which the light strikes the reflector shows separate regions in the physical working of the reflector which include a region where the Bragg effect is dominant as well as a region where total internal reflection plays the largest role. The existence of these regions is proved using reflection measurements. Based on these findings, an estimate is made for the achievable current gain with an ideal reflector and the potential of epitaxial silicon solar cells is determined. Copyright © 2008 John Wiley & Sons, Ltd.     

Flexible Bragg Reflection Waveguide Devices Fabricated by Post-Lift-Off Process

Bragg reflection waveguide devices are fabricated on a flexible substrate by using a post-lift-off process in order to obtain highly uniform grating patterns on a wide range. In this process, the flexible substrate formed by spin-coating on a silicon wafer is lifted-off at the end of fabrication procedures. The flexible Bragg reflector exhibits very sharp transmission spectrum with a 3-dB bandwidth of 0.1 nm and a 10-dB bandwidth of 0.4 nm, which is provided by the grating pattern with excellent uniformity. Athermal operation of the flexible Bragg reflector is also demonstrated through the optimization of thermal expansion property of the plastic substrate by controlling the thickness of two polymer substrate materials. The flexible substrate made of 0.7-mum SU-8 layers sandwiching 100-mum NOA61 film provides an optimized thermal expansion property compensating the thermooptic effect of the polymer waveguide. The temperature dependence of the Bragg reflector is reduced to -0.011 nm/degC by the plastic substrate.     

Ultra-High Transmission Electrowetting Displays Enabled by Integrated Reflectors

A reflector technique for increasing the transmission performance of a back-lit electrowetting display is presented. The electrowetting display pixel structure consists of an opaque oil film that blocks light transmission. Electrowetting with 5-10 V breaks up the oil film and creates a transmissive area for the pixel. With real-world electrowetting materials and device constraints, the transmissive area typically reaches 60% to 80% of the pixel area. By integrating a simple thin-film reflector between the backlight and the remaining oil film area, the effective transmission can be boosted to >90%. This high efficiency is promising for battery-powered applications and for high-brightness sunlight-legible displays.     

Thin film AlGaInP light emitting diodes with different reflectors

The reflectivity versus incident angle of a GaP/Au reflector,a GaP/SiO_2/Au triple ODR(omni-directional reflector) and a GaP/ITO/Au triple ODR was calculated.Compared to AlGaInP LEDs with a GaAs absorbing substrate, thin film LEDs with a Au reflector,a SiO_2 ODR and an ITO ODR were fabricated.At a current of 20 mA,the optical output power of four samples was respectively 1.04,1.14,2.53 and 2.15 mW.The Au diffusion in the annealing process reduces the reflectivity of the Au/GaP reflector to 9%.The differe...     

A simple analytical model of thin films crystalline silicon solar cell with quasi-monocrystalline porous silicon at the backside

An analytical model that simulates the performance of an elementary thin silicon solar cell with a thin film quasi-monocrystalline porous silicon (QMPS) at the backside reflector is developed. A complete set of equations for the photocurrent generated under the effect of the reflected light is solved analytically in each region. The collection of the light absorbed by the QMPS layer has been discussed and the analytical solution of the light-generated current in this layer is derived. The maximum of the photocurrent density calculated in the present study is in accordance with the numerical values established by Bergmann et al. Furthermore, the influence that the layer's number of double porosities and high porosity have on the photovoltaic parameters is studied. It is demonstrated that the photovoltaic parameters increase with the number of double porosities that the layer might have in a given structure. When the QMPS layer is formed by three double-porosity layers 20%/80% and for a 5-μm-thick film c-Si, the backside reflector gives a total improvement of about 6 mA/cm² for the photocurrent density and 3.2% for the cell efficiency.     

高亮度AIGalnP红光发光二极管

对用于提高AlGaInP红光发光二极管(LED)出光效率的分布布拉格反射镜(DBR)和增透膜进行了分析,用金属有机物化学气相沉积(MOCVD)生长了包含DBR和增透膜的LED,在20mA注入电流下,LED的峰值波长为623nm,光强达到200mcd,输出光功率为2.14mW。与常规的LED相比,光强和输出光功率有很大的提高。