基于CO2激光焊接的高温光纤压力传感器

为了满足高温环境下的压力测量需求,研制了一种基于CO2激光焊接的高温F-P光纤压力传感器。介绍了MEMS压力敏感结构的制作过程,研究了传感器各组件之间的焊接工艺,实现了高温F-P光纤压力传感器的无胶化封装。在此基础上,对传感器的温度特性和高温压力性能进行了研究。结果表明,采用CO2激光焊接封装的传感器可靠性高,在高温下信号传输正常,未出现光谱能量衰减现象。在300 ℃高温下,传感器在0~2.5 MPa范围内的测量误差小于0.2 %FS,能够实现高温压力的准确测量。但温度对传感器的影响不可忽略,在实际应用过程中需对传感器进行温度补偿。     

Evaluation of Residual Stress in Flip Chip Using 3-D Optical Interferometry/FEM Hybrid Technique

Abstract:  The residual stress in flip chips was investigated by a hybrid technique of 3-D finite element method (FEM) and 3-D optical interferometry. The residual stress consists of two parts: the chemical shrinkage stress caused by underfill curing and the thermal stress caused by coefficient of thermal expansion (CTE) mismatch and cooling. Warpage and in-plane deformation of the flip chip during the underfill curing and cooling procedure was real-time characterised with an integrated 3-D optical interferometry system. The measurement results were used to evaluate the chemical shrinkage stress and to verify/modify the FEM model for the analysis of thermal stress. It was found that the chemical shrinkage stress under isothermal curing condition is very small in average and negligible. As the difference between the simulated and measured thermal deformation falls within a limited scope, the accuracy of the simulated thermal stress can be guaranteed.     

Optical Differentiation of Distorted Gratings Using Talbot and Double Diffraction Interferometry

The extensions of two techniques recently proposed for applying the concept of grating shearing interferometry to the optical differentiation of quasi-periodic patterns are presented. Various possible detection modes are described and the validity of the experimental results in the case of gratings with large distortions is discussed.     

半导体激光器列阵二元光学准直器的设计和制作

阐述了二元光学元件用于半导体激光器列阵准直的新方法 ,并设计制作了二元光学准直器。针对半导体激光器列阵的特点 ,采用综合平衡方法进行设计和制作 ,使其理论衍射效率超过 5 1 %。     

硅微机械与光纤组合式列阵传感器的研制工艺

系统地介绍了一和中新颖的硅微机械与光纤组合式列阵传感器的特殊制造工艺。在工艺实验的基础上对硅微悬臂梁列阵形成的光刻技术，各向异性腐蚀的机理与方法，梁膜厚度的精确控制，传感器的一体化等技术进行了较深入的研究，并对实验结果进行了详细地分析。这些工艺与常见的ＩＣ工艺兼容，为这类微传感器和执行器的研制打下了较好的实验基础。     

利用光纤和调制半导体激光的准直方法

本提出了一种新的激光光纤准直方法。利用光传播的平行性和直线性，光学准直技术被用于精密地建立几何参数的测量基准，在这些应用中，光束、处理电路的漂移、杂散光是影响测量精度的主要因素。为了消除这些影响，本利用调制半导体激光技术和光纤技术形成准直光束，四象限探测器进行探测，相敏检波技术对光电调制信号进行解调，所有的信号共享同一信号处理信道，且光束的调制频率远离杂散光的频率范围，激光光束漂移杂散光、电路漂移被抑制，在１ｍ范围获得了０．３μｍ的准直精度。     

Multiplexed Long-Base Flexible Optical Fiber Extensometers and Temperature Bragg Sensors Interrogated by Low-Coherence Interferometry

We present a novel concept of quasi-distributed flexible optical fiber extensometers fully compensated from thermal variations. Developed for structural health monitoring applications, the sensors are composed of a combination of intrinsic Fabry-Perot cavities as long-base extensometers, and point-like Bragg gratings inserted along the same fiber used as temperature sensors. This configuration enables a high degree of multiplexing, thus quasi-distributed sensing, and very efficient temperature compensation. Both types of sensors are read by a fiber-optic low-coherence interferometer, used in an original way to measure simultaneously the length variations of the cavities and the wavelength shifts of the Bragg gratings. Finally, we present the experimental validation of the whole measurement system, suitable for concrete structures instrumentation, as it includes an original optical fiber sheath packaging the optical fiber as a flexible sensor.     

二元光学折/衍混合消色差望远物镜设计

首先从光栅衍射理论出发导出衍射光学元件的色散公式，并进一步推导出用一种材料进行折／衍混合消色差望远物镜设计的公式。最后给出全折射型、一个混合型消色差和一个改进型消色差望远物镜的例子，并进行了比较。结果说明，混合型透镜的性能优于全折射型透镜，而改进型消色差物镜的总体性能优于原混合消色差物镜     

Optical Design Problems in Laser Systems

Exact mathematical expressions for the generalized rays of optics prescribed according to an artificial index is applied to obtain ray-trajectory solutions of the waveguide bound modes. Direct mapping of the bound modes via the Milne equation results in polarization-dependent zigzag rays in the film. Their continuation into the evanescent field regions are no longer straight, their curvature being an indication of the inhomogeneity of the field. This extended ray interpretation predicts inter-waveguide coupling effects, while the curvature of the rays dictates the degree of light confinement. For waveguides with a large index difference, the ray is virtually parallel to the waveguide axis at a distance of approximately a wavelength after leaving the film. The Goos-Haenchen shifts obtained from the generalized ray theory agree exactly with those obtained from the usual mode theory.     

刻纹光纤温度敏感特性的理论与实验研究

理论分析与实验研究揭示环境温度变化对刻纹光纤中传输的光功率影响极小，表明刻纹光纤不适于直接用于温度传感测量，在应力，应变等传感测量中也可忽视温度的影响。     

Morphological and Optical Transformation of Gas Assisted Direct Laser Written Porous Silicon Films

Direct laser writing (DLW) of mesoporous porous silicon (PS) films is shown to selectively create spatially separated nitridized and carbonized features on a single film. Nitridized or carbonized features are formed during DLW at 405 nm in an ambient of nitrogen and propane gas, respectively. The range of laser fluence required to create varying feature sizes while avoiding damage to the PS film is identified. At high enough fluence, nitridation using DLW has been shown as an effective method for laterally isolating regions on the PS films. The efficacy in preventing oxidation once passivated is investigated via energy dispersive X-ray spectroscopy. Changes in composition and optical properties of the DL written films are investigated using spectroscopic analysis. Results show carbonized DLW regions have a much higher absorption than as-fabricated PS, attributed to pyrolytic carbon or transpolyacetylene deposits in the pores. Nitridized regions exhibit optical loss similar to previously published thermally nitridized PS films. This work presents methods to engineer PS films for a variety of potential device applications, including the application of carbonized PS to selectively engineer thermal conductivity and electrical resistivity and of nitridized PS to micromachining and selective modification of refractive index for optical applications.     

基于电磁驱动及磁电／电容检测的硅谐振式双轴角速率传感器设计和测试

本文介绍了一种MEMS角速率传感器的设计、制作和测试．该传感器采用硅梁作为支撑和震动的结构．电磁力在驱动模式中被用来激励质量块做往复运动．驱动模式的频率被设计为5955．38Hz．针对另外两个轴向的角速率检测,设计检测模式的频率分别为6151．01Hz和6591Hz．质量块在驱动模式下的最大位移被设计为20μm．在器件的制作过程中使用了湿法刻蚀、电子柬蒸发、阳极键合、等离子体增强化学气相沉淀（PECVD）、lift—off、感应耦合等离子体活性离子蚀刻（ICP—RIE）等MEMS工艺．质量块的尺寸是1440μm×1400μm×33．6μm,硅梁的设计尺寸分别为10μm×562．5μm×33．6μm,10μm×532．5Ixm×33．6μm,芯片的外形尺寸是3127μm×3069μm．为了进行器件测试,搭建了真空测试平台．测试结果表明,驱动模式下器件的谐响应频率为9609Hz,使用磁电检测的模式其谐响应频率为9605Hz．器件中电容检测需要特殊的电路,该电路目前正在搭建中．分析发现实测结果与模拟仿真结果的差异在于加工过程中产生的误差．     

He-Ne激光光阱及对微粒子的操纵北京市自然

分析了He-Ne激光光阱对微粒子的作用.在所建立的He-Ne激光微束的实验装置上用光阱捕获了酵母细胞和空心电介小球,实验验证了光阱的力学效应.实验表明该光阱能实现对微粒子的捕捉、旋转和翻转,能同时捕获多个粒子.从理论和实验上研究了He-Ne激光光阱作用于微粒子的力学效应.     

Design and Optical Trapping of a Biocompatible Propeller-like Nanoscale Hybrid

Designing nanoscale objects with the potential to perform externally controlled motion in biological environments is one of the most sought-after objectives in nanotechnology. Different types of chemically and physically powered motors have been prepared at the macro- and microscale. However, the preparation of nanoscale objects with a complex morphology, and the potential for light-driven motion has remained elusive to date. Here, we go a step forward by designing a nanoscale hybrid with a propeller-resembling shape, which can be controlled by focused light under biological conditions. Our hybrid, hereafter "Au@DNA-origami", consists of a spherical gold nanoparticle with self-assembled, biocompatible, two-dimensional (2D) DNA sheets on its surface. As a first step toward the potential utilization of these nanoscale objects as light-driven assemblies in biological environments, we show that they can be optically trapped, and hence translated and deposited on-demand, and that under realistic trapping conditions the thermally induced dehybridization of the DNA sheets can be avoided.     

大面积激光测速靶光学系统的设计与分析

提出了以微珠玻璃原向反射屏和光纤光锥构建大面积激光测速靶的新方案,对微珠玻璃原向反射屏的反射率和原向反射光斑的光强分布进行了测试分析,并以此作为光学系统设计的依据.实验结果表明:光学系统设计合理,完全可用于各种弹丸初速的实际测量.     

一种用于光传飞控系统的光纤温度传感器研究

利用半导体光吸收原理,设计出一种光纤温度传感器,它可实现强电磁干扰下高空无人机内的环境温度测量,具有体积小,结构简单的特点。该测试仪用GaAs晶片作为温度敏感元件,采用透射式结构,利用双光束补偿原理消除了光路扰动产生的误差。实验结果表明该传感器在-20-85℃的范围内有良好的温度响应。     

Experimental Characterization of Hybrid Temperature and Frequency Effects on the Performance of Transformers on Silicon Substrate

We have performed an experimental characterization of hybrid temperature and frequency effects on the performance of on-chip square transformers. Using measured two-port S-parameters at different temperatures, we extracted and compared the maximum available gain$G_max$and fractional power loss$P_ loss$in each of three transformers (with turn numbers of$N = 2, 3$, and$4$of the primary and secondary spirals, respectively). We found that, as temperature increases, the transformer performance degrades significantly. This is caused by the increase in the conductive loss of metal tracks and the dielectric loss of silicon substrate. However, beyond a certain temperature, such as at 418 K in the case of$ N=4$, further increase in temperature has little effect on performance, mainly because of the constitutive characteristics of silicon substrate. In addition, the decrease in$G_max$and increase in$P_ loss$with temperature depend on the number of turns.