双材料微梁阵列非制冷红外成像技术--微梁阵列热变形的光学读出

针对双材料微梁阵列非制冷红外成像技术的光学读出系统,提出了在谱平面上进行刀口滤波将阵列转角转化为像平面上光强变化的高灵敏度测量技术,并对光学探测灵敏度进行了理论分析.利用该光学读出系统在实验中得到了120℃红外物体的热图像.通过对实验结果的分析和图像处理消除噪声技术,得到该系统在成像温度范围的噪声等效温度差(NETD)约为5K,并对系统噪声进行了讨论.     

基于MEMS和光学读出的非制冷红外成像技术

由于军事和商业应用的巨大潜力,红外成像技术至今仍是研究热点之一。针对本课题组提出的基于MEMS和光学读出的新型非制冷红外成像技术,本文一方面通过有限元仿真分析,详细讨论了新型无基底双材料微梁阵列FPA的热转换效率和热变形效率,另一方面通过光学理论分析,详细讨论了光学读出系统在极限操作下的光学测量灵敏度。理论和仿真分析显示,课题组提出的非制冷红外成像技术的NETD的理论极限与当前制冷型红外成像技术的典型指标相当,约为4mK。同时,本文对设计制作的FPA,在构建的系统上进行了红外实时成像实验和理论仿真分析,显示其系统级NETD已达到110mK。     

光学读出室温物体红外成像

光学读出式红外成像系统是近年来提出的一种新型红外成像技术,它是基于探测双材料微悬臂梁吸收红外辐射后的变形。本文采用了谱平面刀口滤波方法,将双材料(SiNx/Au)微梁阵列接收热像后的转角变形转化为像平面上微梁阵列的像所对应的光强变化,并设计制作了无基底单层膜结构微梁阵列(100×100pixels,微梁尺寸200×200μm2,厚2μm)。用该阵列在光学读出系统中,获得了室温下人体的热图像。该系统在室温时(300K)噪声等效温度差(NETD)达到0.2K。     

光机械式红外探测器中镜面弯曲对探测灵敏度的影响(英文)

光学读出式红外成像技术是近年来研究的热点,本文讨论了镜面弯曲对光学检测灵敏度的影响。由双材料微悬臂梁组成的非致冷焦平面阵列通过体刻蚀工艺加工而成,由于残余应力的影响,制成的焦平面阵列将会发生弯曲,应力导致的镜面弯曲将会降低光学探测灵敏度。本文通过傅立叶光学模拟了镜面弯曲对光学探测灵敏度的影响,并通过实验验证了该模型。实验和模拟结果表明,在镜面曲率为0 .1mm-1时,光学探测灵敏度将会降低到理想情况的40 %。最后我们用这个模型评价了通过表面修饰来提高光学性能的效果。     

光机械式红外探测器中镜面弯曲对探测灵敏度的影响

光学读出式红外成像技术是近年来研究的热点，本文讨论了镜面弯曲对光学检测灵敏度的影响。由双材料微悬臂梁组成的非致冷焦平面阵列通过体刻蚀工艺加工而成，由于残余应力的影响，制成的焦平面阵列将会发生弯曲，应力导致的镜面弯曲将会降低光学探测灵敏度。本文通过傅立叶光学模拟了镜面弯曲对光学探测灵敏度的影响，并通过实验验证了该模型。实验和模拟结果表明，在镜面曲率为0．1mm-1时，光学探测灵敏度将会降低到理想情况的40％。最后我们用这个模型评价了通过表面修饰来提高光学性能的效果。     

光机械式红外探测器中镜面弯曲对探测灵敏度的影响

光学读出式红外成像技术是近年来研究的热点,本文讨论了镜面弯曲对光学检测灵敏度的影响.由双材料微悬臂梁组成的非致冷焦平面阵列通过体刻蚀工艺加工而成,由于残余应力的影响,制成的焦平面阵列将会发生弯曲,应力导致的镜面弯曲将会降低光学探测灵敏度.本文通过傅立叶光学模拟了镜面弯曲对光学探测灵敏度的影响,并通过实验验证了该模型.实验和模拟结果表明,在镜面曲率为0.1mm-1时,光学探测灵敏度将会降低到理想情况的40%.最后我们用这个模型评价了通过表面修饰来提高光学性能的效果.     

基于光学读出的微悬臂梁温度传感器研制

为实现对环境温度的高分辨率、快速、准确测量,设计制作了一种基于光学读出的微悬臂梁温度传感器.由于组成微悬臂梁的两种材料——金和氮化硅热膨胀系数的差异,在温度变化时,梁内部会产生热应力导致其弯曲变形.不同温度下梁的弯曲变形量不同,利用光杠杆方法检测出此变形,经标定后就能实现环境温度的准确测量.实验中设定系统光臂长度为25mm,采用商业化三角形微悬臂梁(长200μm、宽40μm、氮化硅层厚0,6μm,金层厚60nm)对传感器进行了测试,实验结果显示其测量重复性好,温度分辨率达到0.02℃.对于特定尺寸的微悬臂梁,通过优化其双材料厚度比,温度分辨率可达10-4℃,可用于环境温度的精密测量.     

中国科大光力学工作进展

中国科学技术大学光力学实验室近年从事实验力学方法在红外成像、金属物理学以及生化传感等交叉领域的研究,为实验力学带来了新的研究内容,也为相关领域的研究开辟出独特的途径.本文拟对该小组近年来取得的研究进展作一个概述:1)提出微梁阵列FPA变形的高灵敏光学检测法,设计制作出相应的FPA,实现了新概念光学读出红外成像,热成像指标处于国际领先;2)提出用动态散斑研究合金材料锯齿形屈服剪切带,建立了溶质原子与位错交互作用的动态应变时效模型,再现出锯齿形加载曲线和带反复传播的轨迹;3)提出用微梁传感研究大分子/蛋白质构象折叠,检测到构象转变过程中分子间力的相互作用信息和折叠动力学过程,为研究大分子折叠机理提供了一种新途径.     

中国科大光力学工作进展

中国科学技术大学光力学实验室近年从事实验力学方法在红外成像、金属物理学以及生化传感等交叉领域的研究，为实验力学带来了新的研究内容，也为相关领域的研究开辟出独特的途径。本文拟对该小组近年来取得的研究进展作一个概述：1）提出微梁阵列FPA变形的高灵敏光学检测法，设计制作出相应的FPA，实现了新概念光学读出红外成像，热成像指标处于国际领先；2）提出用动态散斑研究合金材料锯齿形屈服剪切带，建立了溶质原子与位错交互作用的动态应变时效模型，再现出锯齿形加载曲线和带反复传播的轨迹；3）提出用微梁传感研究大分子／蛋白质构象折叠，检测到构象转变过程中分子间力的相互作用信息和折叠动力学过程，为研究大分子折叠机理提供了一种新途径。     

基于MEMS的光力学红外成像

非制冷红外成像仪以其优良的性价比和高可靠性而倍受关注。近期 ,非制冷的热机械型红外成像仪有望发展成为新的低价格高性能的红外成像设备。本文提出了一种新型光学读出的红外探测仪。此红外探测仪的核心器件焦平面阵列 (FPA)由无硅基底结构的微悬臂梁阵列构成。每个微悬臂梁独立地把入射的红外热辐射转化为被光学系统探测的热变形。它不需要读出电路、真空腔和制冷装置 ,其理论上的噪声等效温度差接近致冷型红外成像系统 ,而制作成本和难度将大幅降低。制作的无硅基底单层膜结构的FPA ,其单元尺寸为 2 0 0 μm× 1 0 0 μm ,阵列大小为 1 5 0× 1 0 0像素数。实验制作的系统探测到温度为 5 0 0K左右的热物体像 ,热像采样频率为 1 2幅 /秒。     

Absolute phase measurement in extrinsic Fabry-Perot optical fiber sensors using multiple path-match conditions

This paper describes the use of the first and second optical return paths in a moderate-to-high finesse Fabry-Perot sensor to measure the absolute phase in extrinsic Fabry-Perot interferometry (EFPI) sensors. A path-matched differential interferometry (PMDI) using a highfinesse EFPI sensors, a low-finesse Fabry-Perot readout interferometer and a broadband light source consisting of amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA) is used to illustrate the idea. The first and second multiple paths in the Fabry-Perot readout sensor are used to provide two distinct path-match conditions from the same scanning Fabry-Perot readout interferometer. The difference in fringe numbers between the centers of two orders of interference fringe packets formed by the distinct path-match conditions makes possible a simple method of measuring the cavity length of EFPI sensors, which in turn can be used to measure absolute phase and the corresponding strain. Sensor cavity length measurement using the multiple return paths in the high-finesse Fabry-Perot sensor is correlated to that measurement using the modulation transfer function found using an optical spectrum analyzer; the multiple return path technique is then used to make strain measurements on a cantilever beam. Comparisons with resistance strain gage measurements are favorable. Characterization tests indicate that the proposed technique has a cavity length measurement resolution on the order of 1.1 μm, which translates to a strain resolution of 28 με for a 4-cm gage length sensor.     

基于隧道效应的微机械角速率传感器

提出了一种基于隧道效应的微机械角速率传感器的设计方案,还针对隧穿检测和电容检测进行了比较。并指出基于隧道效应的微机械角速率传感器将极大提高传感器的灵敏度。     

Measurement of slopes of structural deflections by speckle-shearing interferometry

A specimen illuminated by coherent light is imaged by a camera through a shearing mechanism so that the speckle from one point on the surface can be made to interfere with the speckle from a neighboring point. The resultant speckle pattern is recorded. By mechanically interfering the recorded speckle pattern corresponding to deformed and undeformed states of the specimen, respectively, using double-exposure technique, a speckle-moiré-fringe pattern is generated. These fringes which depict derivatives of deflections of the specimen are made visible by spatial-filtering technique. Speckle-moiré fringes can also be obtained in real time. This method is a new interferometry and will be referred to as “speckle-shearing interferometry”. Speckle-shearing interferometry has the same function as Ligtenberg's technique. However, it does not have the sometimes inconvenient requirement of Ligtenberg's technique that the surface of the specimen must be of mirror quality. The new technique will be particularly useful in studies of flexural deformation such as flexed beams and plates. Although speckle-shearing interferometry is an interferometric method, it overcomes several of the limitations associated with holographic and speckle interferometries, namely: (1) the setup is simple and does not need laborious alignments of optical components, (2) it does not require stringent mechanical and ambient stabilities, (3) coherent requirement of light is greatly relaxed, and (4) the sensitivity is reduced that somehow fills the gap in sensitivity between moiré techniques and holographic or speckle interferometry.     

Color Stereo-Digital Image Correlation Method Using a Single 3CCD Color Camera

This paper presents a novel color stereo-digital image correlation (stereo-DIC) method using a single 3CCD color camera for full-field shape, motion, and deformation measurements without any sacrifice of the camera sensor spatial resolution. With the aid of a specially designed color separation device using a beam splitter and two optical bandpass filters, images of blue and red colors are simultaneously recorded by the 3CCD camera from two different optical paths. The blue and red channel sub-images extracted from the recorded color images can be analyzed using the regular stereo-DIC algorithm to obtain the full-field three dimensional (3D) information of a test object surface. The effectiveness and accuracy of the proposed technique are demonstrated by a series of real shape, in-plane and out-of-plane translation, and 3D deformation tests.     

Performance analysis of the heterodyne schlieren system

The performance of the electronic heterodyne schlieren system is investigated. The sensitivity, spatial resolution, and dynamic range of the system are calculated. It is shown that these features are improved compared with the conventional intensity schlieren readout technique. Without changing the system setup, the sensitivity and accuracy of the system can be tripled by using the third harmonic of the heterodyne signal. In this case, the spatial resolution and the measurement range are reduced by a factor of three. The system is self-calibrated. For whole field measurements, the method is limited by the camera to milliseconds time scale. However, for selected points measurements fast variations, the order of tens of microseconds, can be measured. The system was evaluated experimentally by measuring the focal length of a weak lens and a multiscale phase plate.     

Distributed strain sensing using frequency-modulated continuous-wave reflectometric optical technique

This paper presents an analysis describing the feasibility of a distributed optical fiber strain sensor whose principle of operation is based on the frequency-modulated continuous-wave (FMCW) reflectometry technique. The system consists of a frequency-swept laser diode and an unbalanced two-beam interferometer. In this system, the test arm comprises a number of single-mode fibers, which act as the sensing fibers, with a mirror at the far end and mechanical splices as the connectors, as well as the reflectors. Theoretical analysis shows that the measuring resolution of the strain is inversely proportional to the length of the sensing fiber. The strain variation of the sensing fiber is measured by demodulating the phase shift of the beat signal using a heterodyne signal processing system, and therefore the requirement of a high precision temperature control of the light source can be eliminated in this way. The comparison between the theoretical and experimental values of the strain resolution showed excellent agreement.