带有力反馈控制的三明治式微机械干涉加速度计

设计了一种静电力反馈控制的三明治式微机械干涉加速度计,加速度计由敏感芯片、半导体激光器、光电二极管以及相应的驱动电路和反馈控制电路组成.敏感芯片为玻璃-硅-玻璃3层结构,通过硅-玻璃键合体硅工艺制成.硅质量块由铝梁支撑,底部玻璃基片上有金属光栅和电极,通过在质量块和底部玻璃基片上的电极之间施加电压可以调节质量块与玻璃基片间的间隙.入射激光照射到敏感芯片上的光栅上,产生衍射光束,其光强随质量块与下玻璃的间距而变化.反馈控制电路通过测量衍射光强的变化来改变质量块与底电极之间的电压,使得质量块与底部玻璃基片的距离保持为入射光波长1/8的奇数倍,从而提高输出线性度,改善灵敏度,增大量程.     

光栅计量型的垂直扫描位移工作台及其误差分析

为满足精密测量中垂直扫描白光干涉以及千分表、电感位移传感器、表面粗糙度触针位移传感器标定对垂直方向的高精度定位和高分辨率运动要求,研制出一种纳米级垂直扫描位移工作台.该工作台采用柔性铰链结构,压电陶瓷驱动位移,满足纳米级微位移驱动要求,同时利用两级杠杆放大结构,扩大了位移行程.针对压电陶瓷驱动的位移随电压变化的非线性特点,利用衍射光栅对压电驱动进行实时监控,对这种非线性误差进行实时补偿.衍射光栅固定在工作台的微定位板上,工作台的移动量可由衍射光栅二次衍射干涉后产生的条纹变化得到.根据衍射光栅的计量特点,分析垂直扫描位移工作台测量误差的主要影响因素.通过试验验证,优化系统误差,进一步提高了垂直扫描位移工作台的定位精度.     

基于衍射光栅的二维纳米位移测量技术

提出了一种基于正交衍射光栅作为测量基准元件的二维激光干涉测量系统.利用正交光栅的空间对称级的衍射光进行干涉,基于多普勒效应,采用偏振检测的方法获得相位相差90°的干涉信号.通过光电检测把获得的正弦和余弦信号进行相位细分,系统可在平面二维方向上实现纳米级的分辨率.该系统相比其他干涉测量系统,测量结构紧凑,环境因素对其影响较小,可应用于较大行程的平面微位移精密检测.     

高精度衍射光栅干涉仪的研制

提出了一种新型的激光衍射光栅干涉仪测量系统,以光栅衍射原理和偏振光学为理论基础,配合正交信号的解相位细分原理,使得该系统可以达到纳米级分辨率.由于光栅干涉测量系统以光栅栅距作为测量基准,相对于传统干涉仪,光栅尺系统受环境因素造成的测量误差影响较小.通过实验校正,得到不同行程范围内光栅干涉测量系统的纳米级重复性误差,新型的激光衍射光栅干涉仪测量系统适合于较长行程的高精度位移测量.     

基于MEMS技术集成硅微棱镜耦合和微流道的近红外表面等离子体谐振芯片

为促进表面等离子体谐振（surface plasmon resonance, SPR）测试技术在片上的实现,提出硅基近红外SPR芯片,由硅微棱镜、金属膜和聚合物微流体通道组成．利用有掩膜和无掩膜各向异性湿法腐蚀加工出底角为25．24。的单微硅棱镜阵列,用有掩膜各向异性湿法腐蚀加工出底角为54．74。的双微硅棱镜阵列,利用聚合物的复制注塑技术加工得到微流体通道．在波长1550nm时进行仿真与实验测试,实验测得以空气、水和乙醇为测试介质的SPR角分别为16．75°、22．58°和22．72°,这些值比以玻璃棱镜加工SPR传感器测得的SPR角要小很多．通过实验表明,近红外SPR芯片可以实现表面等离子体谐振传感器微型化,进而推动微全分析系统的实现,降低其成本并提高其性能．     

深蚀刻玻璃光波导光栅的研究

采用全息法制备了光刻胶光栅，并用该光栅掩膜离子蚀刻，刻得槽深为１．６μｍ的玻璃光栅，再采用Ｋ＾＋／Ｎａ＾＋交换法制备玻璃光波导光栅，用６３３ｎｍ波长激光由一端棱镜耦合输入，经过光栅，由另一端面输出，在实验中观察到多级布拉格衍射，一级布拉格衍射效率最高达９０％。     

微透镜列阵与红外探测器列阵集成芯片的研究

在分析微透镜列阵光聚能原理的基础上,针对背照式256290铂硅红外焦平面探测器列阵 的结构参数,设计了衍射微透镜列阵,使入射光通过硅基底聚焦至探测器的各个光敏面上, 提高光能利用率从而增强探测能力。实验获得了微透镜列阵与红外焦平面集成芯片,并在热成像中取得了良好的结果。     

单片三轴硅微机械振动陀螺仪研究

设计、制造了一种单片集成三轴硅微机械振动陀螺仪.该器件由两个结构完全相同的单轴水平陀螺仪和一个单轴垂直陀螺仪组合而成,三只单轴陀螺仪均采用静电驱动、电容检测的结构形式.采用体硅溶解薄片法制造了该三轴陀螺仪芯片,并对其在空气中的驱动性能进行了初步测试.测试结果表明,该单片三轴硅微机械振动陀螺仪驱动模态的实际谐振频率与理论值之间的最大误差小于5%,满足设计要求.     

TFBG的Fabry-Perot干涉型纵向微位移传感研究

提出了一种利用光纤Fabry-Perot(F-P)干涉结构的微位移传感器,该F-P干涉结构是由双倾斜光纤光栅(tilted fiber Bragg grating,TFBG)沿轴向错开一定距离构成空气腔形成的.入射光经双TFBG及其高反射端面往返传播,从而构成F-P干涉结构.光纤沿纵(z轴)向移动时,F-P腔的腔长发生变化,致使干涉光谱的自由光谱范围随之产生变化.实验验证,该传感器在0~115μm的测量范围内获得了高达0.475nm/μm的灵敏度,较之前提出的光纤光栅型传感器灵敏度提高了近3倍.     

单周期层状位相光栅的衍射效应及其应用

光栅在测试技术及光谱分析中获得了广泛的应用。对入射光波的振幅或光强进行调制的振幅光栅,理论上有25％的衍射光强集中于零级,且因部分栅面被复盖而光能损失严重,效率过低。与此相反,位相光栅的整个栅面具有同样的透射或反射率而仅对位相进行调制,使光强主要集中到所要求的衍射级上。其中,单周期层状位相光栅既可让全部栅面透射或反射光波,又能充分抑制零级衍射光并使衍射光强集中到1级和3级。若不计反射(或透射)和散射损失,则一般由等距单缝构成的透射(或     

基于LPFG微弯特性的高精度位移检测系统

在研究长周期光纤光栅(LPFG)温度及微弯特性的基础上,通过引入聚合物温度增敏封装后的光纤布拉格光栅(FBG)作为解调滤波器,搭建了温度自补偿微位移检测系统.将LPFG粘贴于试件上进行微弯测试,在固定波长处.其插入损耗的变化与弯曲度变化呈线性关系.为解决LPFG带宽宽、谐振波长难以精确测量的问题,选择特定波长的FBG作为滤波器,实现了位移检测系统的功率化解调.同时,对FBG利用聚合物进行了温度增敏封装,使其温度灵敏度与LPFG尽量相同,消除了温度对系统的影响.试验结果表明,传感系统输出的光功率与微位移呈良好的线性关系,位移灵敏度为2μW/mm,分辨力为0.5×10-2 mm.所设计的系统结构简单、灵敏度高、线性度好,不受外界温度干扰.     

光刻法制备聚合物/液晶光栅

将明胶涂覆在表面经过取向处理的带有ITO电极的玻璃基板上，以紫外灯为光源，通过光掩模法，使明胶在光场的引发下发生光化学反应，样品显影刻蚀处理后呈栅状，将液晶注入光栅盒中，形成聚合物／液晶光栅。该光栅衍射效率可利用电场调控。采用He—Ne激光器对所制样品进行测试，结果表明，所制样品的栅结构较好。避免了液晶与聚合物相分离的不完全性和栅条边缘不整齐的现象。制得的光栅其第一衍射级次的开关比为87：1，显示了较好的开关能力。     

三角混合两级杠杆微位移放大机构的设计及性能分析

针对压电执行器和压电驱动平台输出行程有限的问题,设计了一种三角混合两级杠杆微位移放大机构。首先,理论推导了该微位移放大机构的位移放大公式,得到了位移放大比;其次,分析了不同类型两级杠杆结构支点铰链对施加载荷的敏感性;最后,利用ANSYS软件对机构进行静力学和动力学仿真,对机构的相对寄生运动比和固有频率进行了分析。结果表明：当选取直梁形铰链作为两级杠杆结构的支点铰链时,机构对施加载荷的敏感性较强;机构位移放大比理论值与仿真值的相对误差为9.56%,相对寄生运动比为0.348 2,且1阶固有频率最佳。所设计的微位移放大机构具有较小的寄生位移、较强的抗干扰能力和较好的动力学性能。研究结果为压电驱动器或快速反射镜支撑结构实现大量程的位移输出提供了一定的理论指导。     

Mo/Si multilayer-coated ruled blazed gratings for the soft-x-ray region

Two Mo/Si multilayer-coated blazed gratings have been fabricated for operation at soft-x-ray wavelengths above the Si L edge, λ ≥ 12.4 nm, at (near) normal incidence. The sawtooth profile of the grating structure was mechanically ruled into a 200-nm Au film that was deposited onto a plane glass substrate. To smooth the rough Au surface and to prevent interdiffusion of the Au film with the upper Mo/Si multilayer, a carbon film was evaporated onto the Au grating surface of one of the gratings before the deposition of the multilayer coating. We matched the multilayer grating, working on blaze in the third diffraction order, in which an absolute diffraction efficiency of 3.4% at a wavelength of 14 nm was measured, whereas only 1.1% was achieved for a similar grating (without a carbon interlayer). These efficiencies are higher than those obtained for other ruled blazed gratings reported in the literature. As a result of the multilayer and grating periodicity, the wavelength of diffraction can be tuned bya rotation of the grating, which is important for application in a soft-x-ray monochromator.     

Quasi-Talbot effect of a grating in the deep Fresnel diffraction region

Based on the theory of scalar diffraction, the diffraction of gratings in the deep Fresnel diffraction region is developed, and the general formula of the diffraction intensity of the one-dimensional grating is presented by using the Hankel function. Through numerical calculations, some interesting diffraction phenomena are found. In the deep Fresnel diffraction region, the dominant effects, with increasing propagation distance from the grating, are, in order, the geometrical effect, the quasi-geometrical effect, and the interference and diffraction effects. Furthermore, the diffraction intensities vary periodically in the diffraction effect region with increasing propagation distance. Quasi-Talbot imaging of the grating exists in the interference and diffraction regions, and the intensity distributions most similar to the structure of the grating are not at the exact Talbot distances. These phenomena in the deep Fresnel diffraction region are distinct from those in the Fresnel diffraction region. The formation origin of quasi-Talbot imaging of the grating is also discussed, and the numerical calculations powerfully verify the theoretical results.     

Temporal superresolution: An application of frequency filtering by a grating in the resonance domain

Abstract

A diffraction grating in the resonance domain is known to exhibit significant change in diffraction efficiencies with a small change of the grating parameters. It is proposed that this property can be utilized for frequency filtering, when polychromatic light illuminates the grating. As an example, compression of a femtosecond optical pulse is numerically demonstrated with the concept of superresolution. Suppression of zeroth diffraction order by suitably optimized grating structure induces the pulse width to narrow. This scheme considerably simplifies existing optical pulse shaping systems.     

High-efficiency diffractive waveguide lenses by parametric optimization

The first-order diffraction efficiency of a waveguide diffraction grating is maximized, for a wide range of grating periods, by optimization of the effective-index modulation profile. Three different values of effective-index modulation in the range of 0.02-0.11 are considered. The analysis is performed with the thin-grating-decomposition method. The results are verified by electromagnetic grating theory and applied to the construction of diffractive waveguide lenses with an improved overall efficiency. In the neighborhood of the optical axis, the optimized lens structure is a close approximation of a gradient-thickness Fresnel lens. Significant deviations from this shape appear when the local grating period reduces below ~ 15-25λ, where ~ is the wavelength of the guided mode. Near the edges of a high-numerical-aperture lens, where the local period is ~ 3-6λ, an approximate Bragg grating structure is obtained.     

High transmission efficiency for surface plasmon resonance by use of a dielectric grating

The efficiency of the transmission of surface plasmon waves by use of a dielectric diffraction grating is discussed. The Kretschmann device allows us to obtain a surface plasmon resonance that consists of an absorption peak in the reflection spectrum. When surface plasmon resonance occurs, the TM-polarization mode of the incident electromagnetic wave is neither transmitted nor reflected. The procedure to transform an 4bsorption peak into a transmission peak is described. Transmittivity of 68% is obtained for a simple structure that consists of a thin-film layer of Ag coated on a volume diffraction grating and embedded between two dielectric media. The results presented herein were obtained by numerical simulations that were carried out by use of an algorithm based on the rigorous coupled-wave theory.     

自聚焦变栅距光栅设计、制作及特性研究

利用变栅距光栅的衍射光束自聚焦特性,设计和制作了变栅距透射光栅,并对其自聚焦特性进行了研究.采用变栅距光栅的自动生成宏文件程序,优化设计了变栅距光栅的栅距变化.采用光栅扫描电子束光刻的方法制作了中心线数为300 1/mm、适用于355 mm波长的自聚焦变栅距变狭缝光栅.使用三倍频Nd:YAG激光器,研究了制作的变栅距光栅的聚焦特性,并与对氦氖激光的聚焦特性进行了比较.结果表明,主动式设计的变栅距变狭缝自聚焦光栅可以大幅提高衍射光强度和分辨本领,具有重要的应用价值.