光纤光栅位移传感器在边坡监测中的应用研究

针对传统的边坡监测不能依据边坡工程实际实时动态地掌握边坡发展、变形、破坏过程的问题,提出将光纤光栅位移传感器布设在露天矿工程潜在滑动面上对位移数据进行精确采集并预警的方法。该方法根据得到的位移数据掌握边坡变形破坏过程,然后依据边坡发展变化规律判别滑坡的临滑时刻,从而作出及时准确的预警。试验结果表明,将光纤光栅位移传感器应用在边坡监测中能够得到动态的位移监测曲线,同时依此作出的预警十分准确有效。     

Micro-measurement using grating microscopy

In this paper, two quantitative methods to measure micro-deformation using grating microscopy are proposed, a grating diffraction method and a full-field grating phase-shift method. A compact optical transmitting microscope with white light source is reconstructed by developing a loading and recording system. For direct strain measurement, a grating diffraction method is presented. With the help of a Bertrand lens, the Fourier spectrum of the grating is formed on the CCD sensor plane with high image quality. Software for precise, fast and automatic determination of the diffraction spot centroids is developed. Local strains are thus measured with high resolution. For the deformation measurement, a phase-shifting grating microscope method with high sensitivity and spatial resolution is proposed. Phase-shifting is based on the slab refraction effect and is realized via a tilting compensator. The system possesses a high spatial resolution (1 μm), and a displacement precision of 0.1–0.03 μm. The combination of the grating diffraction method and the phase-shifting method in the same test provides simultaneous measurement of strain and displacement, thus demonstrating that the grating techniques are viable in the microscope environment.     

光栅刻划机的建模与仿真方法研究

用于制作母光栅的光栅刻划机的性能指标直接决定最终生产的光栅质量。为此,采用基于虚拟样机的联合仿真策略,代替传统的物理样机开发。利用动力学分析软件Pro/Engineer和控制仿真软件Simulink分别建立光栅刻划机机械动力学模型及控制系统模型,实现机电一体化仿真分析。根据仿真结果确定控制系统参数,实验结果表明,使用该方法可降低开发成本,提高研发效率。     

光栅刻划机金刚石刀具抬落机构控制系统

为了改善传统机械式光栅刻划机的刻划性能,提出了一种新型光栅刻划机金刚石刀具抬落机构。介绍了光栅刻划机及抬落刀机构结构组成,并根据需求分析选用压电陶瓷平台作为执行器件。搭建了一套抬落刀控制系统并完成硬件设计,针对光栅刻划工艺需求,设计抬落刀控制系统软件。系统采用总线通信方式,制定串口通信协议。结果表明,该新型机构机械结构简单、可实时控制、精度高、无振动和发热,提高了刻划光栅的质量和刻划效率。为了改善传统机械式光栅刻划机的刻划性能,提出了一种新型光栅刻划机金刚石刀具抬落机构。介绍了光栅刻划机及抬落刀机构结构组成,并根据需求分析选用压电陶瓷平台作为执行器件。搭建了一套抬落刀控制系统并完成硬件设计,针对光栅刻划工艺需求,设计抬落刀控制系统软件。系统采用总线通信方式,制定串口通信协议。结果表明,该新型机构机械结构简单、可实时控制、精度高、无振动和发热,提高了刻划光栅的质量和刻划效率。     

A new method for fabrication nano-porous aluminum grating array

The fabrication technique of highly ordered anodic porous alumina membrane by anodization of Al and the obtained membrane as a mask to the fabrication of 100 nm period antireflection grating hole are described. The two-step anodizing process improves the quality of the nanohole because the periodic seeds are generated by the first anodization. Antireflection grating structures are fabricated by using ordered anodic porous alumina mask and etched by SF₆ fast atom beam on silicon wafer. The reflectivity of the antireflection grating structures is measured and compared with that of the calculated value and the polished silicon surface.A part of this work was performed in Venture Business Laboratory in Tohoku University, Japan.     

Injection molding and injection compression molding of three-beam grating of DVD pickup lens

The objective of this paper is to investigate the application of injection molding and injection compression molding processes to produce diffraction gratings. A mold was designed to produce a diffraction rating connected with the fixed bushing. The combined part was verified to have a good diffraction performance. Integrated grating eliminates the assembly cost and error. Photolithography was applied to make the mold insert. The Taguchi method and parametric analysis were applied to study the effects of molding parameters on grating quality. The design, fabrication of structured mold surfaces and the results of the replication by injection molding (IM) and injection compression molding (ICM) are presented and compared. The diffraction angle of ICM grating is more accurate than that of IM grating. Grating made by ICM has a much smaller warpage than that made by IM. The diffraction pattern shows that ICM is a better process than IM to replicate a diffraction grating.     

沥青混凝土路面光栅应变传感器的试验研究

疲劳是沥青路面设计标准之一,沥青混凝土的疲劳失效与沥青层底拉应变值的大小相关.为了准确测得在实际车辆荷载作用下沥青层底的应变响应,采用光栅应变传感器代替传统的电信号传感器进行路面应变测量的试验研究,结果表明光栅传感器在抗振动、抗电磁干扰等方面性能较好,试验结果与路面结构和材料类型相符,能够满足路面应变测量的要求.     

基于机器视觉的编码器光栅装配偏心调整技术

编码器光栅装配的过程中, 光栅实际回转中心与编码器主体轴的回转中心很难重合, 这样会影响编码器的输出信号的精度。为了解决编码器光栅与主轴的偏心问题, 提出一种基于机器视觉的光栅偏心自动调整系统。对光栅表面图像进行分析处理, 对边界跟踪提取及基于Hough变换圆弧检测等算法进行研究。根据光栅装配要求搭建了偏心计算系统的硬件系统。对光栅图像进行预处理及形态学操作, 在分析提取光栅基圆部分圆弧边界的基础上, 通过Hough变换的圆弧检测原理还原出光栅基圆并标定其圆心。介绍了系统通过多幅光栅基圆圆心拟合回转圆, 确定光栅偏心位置。实验结果表明, 基于机器视觉的编码器光栅偏心计算方法成功计算出光栅与主轴的偏心位置, 为光栅偏心调节奠定了基础。采用光栅偏心计算系统在编码器光栅的装配作业中具有很好的可行性。     

啁啾光纤光栅的光谱特性研究

在啁啾光栅中2个模式之间会发生耦合,要了解啁啾光栅的物理和传感特性,提高反射谱的精度,就必须对啁啾光栅的耦合模理论做深入研究。通过啁啾光栅的耦合方程,并采取合适的坐标变换,利用Matlab进行了数值模拟仿真研究,分别讨论了啁啾光栅耦合模型在不同的折射率调制、不同光栅长度、不同光栅周期和啁啾系数对啁啾光纤光栅反射谱的影响,进一步的研究了啁啾光栅的光谱特性。     

Electromechanical characterization of a new micro programmable blazed grating by laser Doppler vibrometry

The prototype of a new micro programmable blazed grating driven electrostatically was fabricated using a two-layer polysilicon surface micromachining process. And initially, to characterize its electromechanical performances, such as the driving voltage versus displacement relationship, frequency response and step response, the laser Doppler vibrometry was employed. The measured results reveal the pull-in voltage of 110–115 V, resonant frequency of 78 KHz, quality factor of 2.89, adjusting time of 12 μs, and damping ratio of ~0.68 for the achieved grating sample. As a result, the grating functions well electromechanically. As for its optical performances, a number of optical experiments are in progress.     

基于CO2激光器的长周期光栅制作及实验

长周期光纤光栅(LPFG)作为一种重要的无源光器件,以其独特的性能和优势被广泛应用于光纤通信与传感领域。近年来发表了许多不同的LPFG制造方法,但产品可靠性依旧是需要解决的关键问题。提出用CO2激光熔融拉伸法制备长周期光纤光栅,改善了在LPFG制备中各种因素影响导致刻写失败的问题,该方法采用CO2激光器对光纤进行加热软化,在步进电机的恒定拉力下拉锥,重复在据上一锥形中心一个光栅周期的位置处加热拉伸,得到在波长为1539nm处出现最大衰减峰,峰值大于15dB的长周期光纤光栅,提高了LPFG的制备成功率及一致性。并对产品的可靠性进行验证,测试其温度、轴向应力的敏感特性。该研究在光纤激光系统及其应用的光学器件方面有较大应用潜力。     

Characterization method for new resist formulations for HAR patterns made by X-ray lithography

At the Karlsruhe Institute of Technology (KIT), Institute of Micro Structure Technology (IMT) high aspect ratio (HAR) micro structures are manufactured by means of deep X-ray lithography and gold electroplating (LIGA technology). The technology is used to fabricate grating structures for differential phase contrast X-ray imaging (DPCI). Using an epoxy based negative resist material; electroplated grating structures are fabricated having absorber lamellas with heights up to 100 μm and a period down to 2.4 μm. However, in DPCI there is an increasing demand for improved quality gratings with periods down to 1 μm, areas larger than 50 mm × 50 mm with a high homogeneity in terms of the lamella height distribution and defect-free grating patterns. Pattern deformations are due to limited mechanical stability of the resist during the development process as well as to resist shrinkage during crosslinking, affecting mostly gratings with small periods and HARs. The purpose of this contribution is to present a methodology for the characterization of different epoxy based negative resist formulations, aiming to increase the quality of the HAR free standing grating lamellas by increased mechanical stability of the resist.     

写入参数对光纤布喇格光栅反射特性指标的影响

给出了光纤光栅各种制作方法间的相互关系框图.用Matlab数值仿真方法研究了光栅初始写入参数对其峰值反射率和反射带宽的影响规律.此外分析了波分复用系统中传感光栅峰值反射率对其测量范围的影响,以及通信系统中光栅滤波器的波长选择问题.研究结果有助于指导光栅制作,并根据具体应用场合的需求选择光栅参数.     

A perceptual evaluation of grating frequencies and velocities in the analysis of dynamic images

Dynamic images that possess beauty and are user-friendly can increase the use of digital technology. In addition to information conveyance, dynamic images also act as a communication bridge in the human–machine interface. Dynamic images are widely used in the application of digital media. Therefore, understanding the visual effects of dynamic images on viewers is a very important issue. From a visual communication design perspective, dynamic images influence not only image quality, but also the viewers’ perception and impression of the displayed image. In the contemporary age characterized by universal usage of dynamic images, designers should attain synchronized knowledge and understanding of relevant media technology so as to present preferred design quality in the management of digital design such as animation design, Web page design, multimedia design, and so on. The current study noted that psychological effects such as viewers’ visual attention, preferences, and understanding were more important than image quality. Therefore, this study adopted the viewpoint of “visual design” and conducted a perceptual evaluation of grating frequency and grating velocity. The pair-comparison method and scale method were adopted in the research methodology to simplify perceptual evaluations and enhance their validity. The purpose of this study was: (1) To propose recommendations for displaying dynamic images and improving image performance using perceptual evaluation methods. (2) To examine the influence of psychological factors on viewer’s comfort when they experience dynamic images. (3) To identify the best grating feature combinations that meet viewer’s psychological characteristics and propose recommendations for dynamic images design. The study concludes that it is useful to establish criteria for evaluating users’ perception and to, develop perceptual evaluations of dynamic images. It is recommended that designers find a balance between watching a moving imaging display “clearly” and watching it “comfortably” for successful reception by the viewer.     

演化算法求解光纤光栅反问题的研究进展

对演化算法求解光纤光栅反问题的研究进行了综述。光纤光栅的反问题即从给定的光纤光栅反射谱（或透射谱）,重构得到光栅的长度、周期、折射率调制深度等参数,以及应力、温度分布等,是在传感和通讯领域都会遇到的一类重要问题。演化算法由于具有计算简单、普适性强、潜在的并行性等优点,近年来被广泛用于求解光纤光栅的反问题,其中主要有遗传算法、模拟退火算法、粒子群优化算法等。文章分析了演化算法求解光纤光栅反问题的优势和不足,并对其研究前景进行了展望。     

一种新型光纤布拉格光栅气体泄漏检测传感器

提出了一种新颖的基于光纤自加热效应的气体泄漏检测用传感器,不仅可对管道连接处等易发生泄漏的部位进行实时监测,还可提供定量的有关管道泄漏速度的数据。泄露到光纤外部的泵浦光能被附着在光纤光栅外部的金属涂敷层吸收,导致温度上升,改变了光栅的栅格周期,进而影响了光栅的谐振波长。当有气流通过光纤光栅时,由于热量被带走,导致光纤光栅温度变化,通过监测谐振波长的改变即可求得气体的泄漏速度。为简化信号解调方法,利用长周期光纤光栅的边沿滤波器特性,实现光纤光栅传感波长的解调。实验通过控制CO2的流速,证实了该方法的可行性。     

圆形磁耦合截面构建的新型时栅位移传感器

现有磁场式时栅位移传感器暴露出机械加工齿槽等分性差和线圈绕制参数一致性差,导致耦合磁场形成的电信号质量较差的问题.针对以上问题,提出了一种以圆形截面铁磁材料替代传统类矩形截面铁磁材料构建耦合磁场形式的传感器设计方法,该方法采用标准件作为基本阵列导磁单元,并以定制的精密线圈绕组设计一种新型的变磁阻式时栅位移传感器.文中首先利用有限元软件ANSYS Maxwell对理论模型的可行性进行了仿真验证,然后通过精度实验获取了误差范围在±1.3"内的误差曲线,仿真与样机实验验证了新型传感器设计方案的可行性.该方法的应用规避了传统的线切割开槽绕线的机械加工形式,可以在有效提高电信号质量的同时大大提高了时栅的生产效率,有利于时栅位移传感器产品化进程的推进.     

ADC参数对光栅莫尔信号细分影响研究

莫尔信号细分是光栅传感器应用的必要环节,幅值分割法是实现莫尔信号细分的重要手段.为减小信号质量对细分结果造成的影响,误差补偿成为细分实现过程中必不可少的单元.本文针对数字式幅值细分方法开展研究,针对ADC参数对光栅莫尔信号误差补偿和细分效果的影响进行分析,建立ADC参数与莫尔信号直流补偿、幅值补偿和细分倍数之间的量化模型,设计并开展了直流和幅值补偿效果实验.研究结果表明:不同位宽的ADC对莫尔信号误差补偿和细分效果的影响不同,在本文模型的基础上,ADC位宽应提高1 bit～2 bit.研究成果对于莫尔信号数字式幅值分割细分系统的工程实现具有一定的指导意义和参考价值.     

Modeling of grating/moiré based micro motion sensor

 The design of a micro optical motion sensor is proposed. Fourier series analysis is used to determine the optical transmission function (OTF) of gratings. The optical flux generated by a grating (pair) and received by photodetector is then calculated through an integration of the OTF over the receiving window. A general relationship between photo-detector output current and grating translation displacement is finally established. The analysis is carried out for linear binary grating sensors, with single and double grating sensors. The influence of grating (pair) structure and receiving window on sensor sensitivity and linearity of output response is investigated. A numerical work is completed to simulate the various cases of optical structure design. Several types of photoresist gratings are fabricated and are used to experimentally characterize the grating sensor. The tested result is found to be in general agreement with the analysis result.     

基于模拟退火算法下多位相型达曼光栅分束器的设计

针对传统达曼光栅分束器衍射效率与光强度均匀性低等问题,提出了一种基于模拟退火算法下多位相型达曼光栅分束器的设计方法;基于标量衍射理论,对多位相型Dammann光栅分束器的相位结构设计进行研究;在原二值型突变点坐标的基础上,使用模拟退火算法对光栅一个周期内的位相结构进行离散、调制,并合理的控制目标函数来对相位结构进行优化设计;其次,以9×9点阵Dammann光栅分束器的位相结构设计为例进行仿真分析,得到了衍射效率为85.3%、光强不均匀性为0.095 2%、均方根误差为8.2×10^-5的位相型分束光栅;最后,进行实验验证,得到衍射效率达到73.5%、光强不均匀性达到10.0%、均方根误差达到0.255;结果表明,该方法具有优越性和实用性,为实际应用中三维测量结构光的产生提供了理论基础。