基于高速摄影动态测试微陀螺振动

针对微机电系统(MEMS)特征尺寸小,常用的动态测试方法和系统还有一定的缺点等问题,本文在介绍MEMS常见的三种动态测试方法的基础上,给出了一种基于高速摄影的微陀螺振动动态测试系统。介绍了系统的硬件架构和软件功能。在动态测试的关键算法上,应用Otsu算法对图像进行分割,使用感兴趣区域(ROI)和不变矩方法得到振动曲线,通过幅频分析得到微机械陀螺的振动特性。实验结果表明:使用这种方法测量振幅的精度达到了0.1 μm;频域测量的重复性和一致性也较好。这种动态测试方法稳定可靠、精度高、抗干扰能力强,可以极大地减少计算量,提高系统运行速度。     

Micro-spectrophotometer based on micro electro-mechanical systems technology

A new mini-spectrophotometer is developed by adopting micro-silicon-slit and micro-silicon-fixer, which are based on micro electro-mechanical systems (MEMS) technology. Both the micro-silicon-slit and the micro-silicon-fixer have their own features, such as small volume and high precision, which are laid out and analyzed later. Meantime, through the analysis of the sample cell’s optical characteristics that have some impacts on the linearity of the spectrophotometer, a relationship equation, which is about the impact of the refractive index of the sample cell and the tested medium on the variety of the transmitted light intensity and the absorbency, is put forward. When the water and the air are taken as the referenced medium, the experiments demonstrate that the difference of the refractive index of the references does not influence the correlation coefficient r and the slope of the absorbency-concentration curve. The final results show that the new mini-spectrophotometer with micro-silicon-slit and micro-silicon-fixer is worked out, its correlation coefficient r > 0.999, and its refractive index resolving power is better than 0.01. __________ Translated from Optics and Precision Engineering, 2006, 14(6): 990–997 [译自: 光学精密工程]     

基于声发射技术的微切削加工表面形貌监测

采用声发射技术对工件材料为A16061-T6的微切削表面轮廓进行了实时测量.采集监控微切削加工表面时产生的声发射均方根信号,并与表面轮廓仪测得的结果进行对比.研究表明,声发射均方根信号与微切削表面形貌很好的相对应,因此,声发射技术适于微切削表面形貌的监测.研究了切削用量(每齿进给量和主轴转速)与表面形貌之间的关系,微切削的每齿进给量对表面粗糙度影响较大.     

Investigation on the determination of flow direction using two parallel cylindrical hot film sensors

Measurement of instantaneous air flow velocity with high frequency can be carried out by using a hot wire anemometer (HWA). HWA works on the basis of heat transfer rate from hot wire to the fluid flow, therefore directional identification of the air flow using hot wire anemometer is a difficult task. By using two parallel cylindrical hot film sensors a probe was built. By considering the wake and heat effect of the upstream sensor on the downstream sensor, direction of the air flow can be identified. In this work, the wake and heat effect resulting from the upstream sensor to the velocity measurement, by the downstream sensor was studied. This measured velocity is dependent of the following factors namely; air velocity, upstream sensor overheat ratio, distance between the two sensors and turbulence intensity of the flow. As a result it was found that the manufactured probe with sensor distance of 1 mm apart is capable of measuring reverse flow measurements of up to 20 m/s for a moderate turbulent flow.     

基于阿基米德螺旋线的低g值微惯性开关

低g值惯性开关是一种对线加速度敏感并在施加的加速度作用下完成闭合的惯性装置。由于微小尺寸的限制,低g值(1-30 g)惯性开关只能设计为微质量块和低刚度支撑梁的结构。为了获得低刚度,设计了基于阿基米德螺旋线的平面螺旋梁结构。微开关由一个带触点的基座、一个惯性敏感单元以及框架和封盖组成。惯性敏感单元则由一个居中的质量块和支撑它的螺旋梁组成。在加速度作用下可动的质量块发生位移,与其下的触点接触,实现开关的闭合。惯性敏感单元采用有限元软件ANSYS进行分析,采用UV-LIGA工艺制作。进行了离心试验以获得低g值惯性开关的闭合门限。经3次测试,闭合门限值分别为21.22,21.39和21.20g,平均值为21.27g。测试结果表明,低g值惯性开关具有0.5g的闭合精度,多次测试重复性较好。     

基于嵌入式系统的足球机器人底层控制系统

为简化足球机器人底层控制系统软、硬件设计,提高系统的实时性和可靠性,采用32位嵌入式系统(ARM),取代目前常用的8位单片机作为控制器的技术方案.详细说明了系统设计原理、实现方法及软件流程图.研究表明,系统具有功耗低、控制精度高、运算速度快、体积小的优点,便于机器人功能的扩展和升级.     

GPS的微型系统及其制导(英文)

基于微型飞行器(MAV)尺寸小、载重及能量供给有限,难于获取完整的飞行状态参数,对机载的设备和导航控制系统要求很高等特点,提出了一种应用于翼展680 mm的电动微型飞行器的基于航迹角度和偏航距误差的几何导航控制算法,并利用MEMS传感器设计了飞行控制系统,给出了PID控制率.Matlab仿真试验表明,该系统在3种PID控制率下均可很好地实现导航控制,偏航控制误差低于30 m;空中飞行试验表明,提出的算法有效地实现了电动微型飞行器的导航控制飞行,在2级风情况下,偏航误差低于30 m.     

Experimental investigation of aerodynamic effects of probe on heat transfer from hot-wire sensors at vertical and horizontal orientations

Aerodynamic effects due to hot-wire anemometer (HWA) probe directly influence heat transfer from the probe sensor and result in reduced accuracy in two-dimensional measurements. This experimental research investigates the aerodynamic effects for hot-wire sensors through the study of some important factors such as probe geometry, flow scheme (velocity and direction) and orientation of the probe relative to the flow direction. In addition, flow velocity field between the prongs of a 10:1 model of a single normal probe is explored at different velocities and yaw angles, both at vertical and horizontal orientations of the probe. Results indicate that in vertical orientation, heat transfer from the sensors is always higher than horizontal orientation. Moreover, the aerodynamic effects cause a velocity increase of up to 6% in the vicinity of the sensor. In addition, the presence of the sensor in the flow, generates low-velocity field in the flow wake and a minor rotation of the flow in the vicinity of the sensor, which result in reduced heat transfer from the sensor in horizontal orientation compared to the vertical orientation.     

米级弯月面化学薄膜涂覆装备的研制

弯月面化学涂膜技术因其具有大面积、低成本以及高效率等优势成为继旋涂、喷涂等传统涂膜工艺后极具发展潜力的新型化学薄膜涂覆技术。本文针对国家某重大项目对米级光学元件表面的化学薄膜涂覆需求,对基于弯月面涂胶的技术原理进行了系统研究,分析了涂胶压强、基片和狭缝间距以及材料亲疏水性与涂胶面形态的关系,实现了对弯月液面的精密调控并研制出基于弯月面化学薄膜涂覆技术的装备,在1 400mm×420mm尺寸玻璃基片上实现了光刻胶的均匀涂覆,使整体胶膜厚度误差4%,满足了米级元件表面精密化学薄膜的涂覆需求。     

基于自适应进化算法的膜系自动设计

为获得性能更好、更易实现的膜系,提出一种基于自适应进化算法的膜系自动设计方法,并将该方法与常用设计方法进行比较。通过增益平坦滤光片、高反膜的实例优化表明,在相同设计要求下,用该进化算法可以得到更加合理的膜系结构,而且膜系结构简单,设计灵活,容易实现。理论和实践均表明该方法是高效和可靠的。     

多层周期性薄膜结构的耦合波方法的研究

在分析耦合波方法与传输矩阵法相互联系的基础上以短波通薄膜滤光片为例,分别计算了正入射和斜入射情况下的修正耦合波方法的计算结果并与一般耦合波法、传输矩阵法计算的结果进行了比较,数值计算的结果表明在入射角度不是太大情况下,修正耦合波方法完全可以替代传输矩阵法对多层周期性薄膜结构进行分析和设计。     

微型膜结构全光纤珐珀干涉高温传感器

制作了一种微型膜结构的全光纤在线珐珀干涉式高温传感器。该传感器是在单模光纤端面依次熔接一段大芯径空芯光纤和一段研磨的多模光纤膜片而构成的,因此,温度引起的珐珀腔光程差改变量由空芯光纤的热膨胀和温度引起腔内压强改变从而改变膜片的扰度两部分组成,从而使相同温度变化下传感器的光程差变化量更大,分辨率更高。实验结果表明,在100～650℃,该传感器单位温度变化的光程差变化量约为1.029 nm,温度分辨率约为1.5℃,测量线性度约为0.996 7,且滞回小,重复性好。这种膜结构的全光纤珐珀干涉式高温传感器因其体积小,温度分辨率高,将在多点高温测量领域有好的应用前景。     

Experimental study on response of hot wire and cylindrical hot film anemometers operating under varying fluid temperatures

The working principle of constant temperature anemometer (CTA), used for fluid velocity and/or turbulence measurements, is based on convective heat transfer from a sensor (a hot wire or a hot film) to the fluid being measured. Response of a CTA, working in temperatures other than its calibration temperature, involves errors which must be corrected for reliable measurement data. We have experimentally studied the effect of variations in fluid temperature on the response of hot wire and cylindrical hot film anemometers, and have discussed the application of different correction factors. Effects of overheat ratio (sensor temperature) and fluid velocity on the CTA output voltage correction factor have been discussed. The results show that the error in the CTA response depends on the sensor temperature, and it shows a decrease with increasing sensor temperature (increasing overheat ratio). The results also show that the error correction factor depends on the overheat ratio and fluid velocity. The required error correction factor also depends on whether the fluid temperature decreases or increases with respect to the calibration temperature of the CTA. In spite of differences in sensor characteristics, our work on cylindrical hot film sensors shows that the correction factors for hot wire and hot film sensors are similar and close in magnitude.     

基于改进型遗传算法的薄膜厚度及光学常数反演

准确的测量薄膜的厚度和光学常数,在薄膜的制备、研究和应用中都十分重要。借助Cauchy色散模型和P阶评函数,通过薄膜透过率测量曲线,用改进的遗传算法对透过率曲线进行全光谱拟合,从而反演得到薄膜的厚度和光学常数。理论验证是对电子束蒸发制备的TiO_2和反应磁控溅射制备的Si_3N_4薄膜进行测试拟合,计算得到的结果与文献报道的一致,误差小于0.5%。     

基于等效层理论的薄膜滤光片中心波长消偏振膜系设计

针对薄膜滤光片倾斜入射时产生的偏振光中心波长分离现象和偏振相关损耗,本文利用等效层理论设计了倾斜入射下中心波长消偏振的100GHz信道间隔滤光片膜系结构,实现了薄膜滤光片的角度和波长调谐。首先通过相位关系分析,计算了滤光片间隔层的消偏振等效折射率,实现了不同偏振光中心波长的对准。然后,根据等效层理论,设计三层对称膜层结构实现了对间隔层中心波长消偏振等效折射率的替换。与原有的五层规整低偏振薄膜滤光片相比,本文提出的膜系结构更为简单,对消偏振等效折射率的替换更为精确。仿真和实验结果表明:该膜系结构的薄膜滤光片能实现0~20°倾斜入射的偏振光中心波长对准,偏振光波长偏离度小于0.03nm,波长调谐范围能达到35nm。     

基于神经网络的多层薄膜结构红外辐射计算和逆向设计

通过设计优化微纳光子结构实现红外辐射光谱调控已成为一个研究重点。近年来,神经网络逆向设计因其自由度高,速度快,性能好等优势,引起了广泛关注。提出了基于神经网络的微纳光子结构红外辐射计算和逆向设计。具体来讲,即针对多层介质薄膜结构,建立多层感知机神经网络模型,通过对样本数据的训练建立多层薄膜的厚度与其红外辐射光谱的映射关系,从而实现了薄膜结构的辐射光谱计算及逆向设计。同时将设计出的薄膜应用到辐射制冷领域。结果表明,即使是在3%的太阳辐射吸收和6 W/(m2·K)的非辐射换热系数的情况下,薄膜辐射制冷器依然能够将温度降低到低于环境温度7℃左右。该研究成果将对红外辐射等应用领域产生重要的影响。     

基于离子束溅射Ta2O5薄膜的紫外吸收膜技术

为获得高性能紫外激光薄膜元件,急需研制紫外高反射吸收薄膜,实现吸收损耗的精确测量。本文采用离子束溅射技术,通过调控氧气流量实现了具有不同吸收的Ta_2O_5薄膜的制备。以Ta_2O_5薄膜作为高折射率材料,设计了355nm的紫外高反射吸收薄膜。采用离子束溅射沉积技术,在熔融石英基底上制备了355nm的吸收薄膜,对于A=5%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,95.0%和4.9%;对于A=12%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,87.4%和12.5%。实验结果表明,采用离子束溅射沉积技术,可以实现不同吸收率的355nm高反射吸收薄膜的制备,对于基于光热偏转测量技术的紫外光学薄膜弱吸收测量仪的定标具有重要的意义。     

Studies on thin film based flexible gold electrode arrays for resistivity imaging in electrical impedance tomography

Practical phantoms are essential to assess the electrical impedance tomography (EIT) systems for their validation, calibration and comparison purposes. Metal surface electrodes are generally used in practical phantoms which reduce the SNR of the boundary data due to their design and development errors. Novel flexible and biocompatible gold electrode arrays of high geometric precision are proposed to improve the boundary data quality in EIT. The flexible gold electrode arrays are developed on flexible FR4 sheets using thin film technology and practical gold electrode phantoms are developed with different configurations. Injecting a constant current to the phantom boundary the surface potentials are measured by a LabVIEW based data acquisition system and the resistivity images are reconstructed in EIDORS. Boundary data profile and the resistivity images obtained from the gold electrode phantoms are compared with identical phantoms developed with stainless steel electrodes. Surface profilometry, microscopy and the impedance spectroscopy show that the gold electrode arrays are smooth, geometrically precised and less resistive. Results show that the boundary data accuracy and image quality are improved with gold electrode arrays. Results show that the diametric resistivity plot (DRP), contrast to noise ratio (CNR), percentage of contrast recovery (PCR) and coefficient of contrast (COC) of reconstructed images are improved in gold electrode phantoms.     

基于精密刻划及薄膜沉积技术的光盘分束光栅研制

尝试了采用光栅刻划和镀膜技术相结合研制光盘分束光栅的方法。采用光栅刻划机在金属膜上刻制占宽比为1:1的黑白光栅,并由黑白光栅翻制出制作光盘分束光栅的掩模版。通过掩模版对涂覆在K9玻璃基底上的光刻胶实施曝光和显影形成光刻胶矩形浮雕光栅,在理论设计的误差允许范围内,对此浮雕光栅沉积SiO2薄膜、去除残余光刻胶后得到SiO2矩形光栅母版,再经复制工艺制作了环氧树脂光盘分束光栅。测试结果表明,利用光盘分束光栅的纵向和横向加工误差的互补性,可以使光栅辅助光束与读写主光束强度之比的误差控制在±0.03之内。     

SiH2CL2-NH3-N2体系LPCVD Si3N4薄膜因素分析

以二氯甲硅烷和氨气分别作为低压化学气相淀积(LPCVD)氮化硅(Si3N4)薄膜的硅源和氨源,以高纯氮气为载气,在热壁型管式反应炉中反应生成Si3N4薄膜.考察了工作压力、反应温度、气体原料组成等因素对Si3N4薄膜淀积速率的影响.结果表明Si3N4薄膜的生长速率随着工作压力的增大单调增大,随着原料气中氨气和二氯甲硅烷的流量之比的增大单调减小.随着反应温度的升高,淀积速率逐渐增加,在840 ℃附近达到最大,随后迅速降低.在适当的工艺条件下,制备的Si3N4薄膜均匀、平整.较低的薄膜淀积速率有助于提高薄膜的均匀性,降低薄膜的表面粗糙度.