光学材料和光学薄膜的光热表征(英文)

光热技术用来测量样品的光学和热特性。简要介绍了光热技术及其在光学薄膜测量和钛蓝宝石激光晶体表征中的应用。光热技术可以提供纯光学光谱学所无法提供的、类似光-热能量转换效率之类的信息。光热技术已被用作质量测试和改善现代光学制造的有用工具。     

液体环境中的光热微驱动方法与技术研究

提出和发展了适用于液体(水)环境的光热微驱动技术及光热微驱动机构(OTMA).建立了水环境中OTMA膨胀臂在激光照射下的光热膨胀模型,基于有限元分析推导出膨胀臂的温升分布公式,并对长度1080μm、宽度90μm的膨胀臂在4 mW激光照射下的温升分布进行了仿真,理论研究表明了液体环境中光热微驱动技术的可行性.设计与微加工...     

激光微加工对陶瓷表面化学镀铜的影响研究

采用扫描电镜(SEM)、X射线光电子谱(XPS)、X射线衍射能谱仪(XRD)等手段比较激光微加工处理前后陶瓷表面形貌发生的变化,探讨了激光微处理在陶瓷表面无敏化活化化学镀铜工艺中的作用.结果表明,陶瓷基底经激光处理后,其表面成分并未发生改变,但其表面活性增强,从而促进了化学镀铜反应的进行.     

基于Labview的激光光热法界面热阻测量系统

根据激光光热法原理,设计了一套低温下界面热阻测量系统,通过Labview操作平台实现对实验温度的精确控制以及对实验数据的自动采集记录。该实验系统能够实现低温下超导带材与导冷材料间界面热阻的测量,为研究直接冷却条件下超导磁体的应用提供实验依据。     

光热敏感型羧甲基壳聚糖纳米微球的制备及光热性能

羧甲基壳聚糖因其具有良好的水溶性和生物相容性,被广泛应用于生物医学领域。以天然可降解高分子羧甲基壳聚糖为载体,在引发剂过硫酸钾的作用下,通过自由基组合法将N-异丙基丙烯酰胺接枝到羧甲基壳聚糖上,然后在香草醛的交联作用下,采用乳化交联法制备一种负载光敏剂吲哚菁绿(ICG)的新型光热敏感型羧甲基壳聚糖微球,通过傅里叶红外(FT-IR)、核磁(1H-NMR)及扫描电镜(SEM)对共聚物结构及微球形貌进行表征,考察了油水比、转速、香草醛、乳化时间对该纳米微球包载阿霉素载药量的影响,并研究了其光热性能。结果表明,FT-IR和1H-NMR分析证明,N-异丙基丙烯酰胺成功接枝到羧甲基壳聚糖上;SEM分析可知,纳米微球外观呈球状,分布均匀,平均粒径为143 nm。油水比为20∶1,转速为600 r/min,香草醛量为1 mL,乳化时间3 h的微球载药量最高为19.32%。同时,通过改变外界环境条件,纳米微球能缓慢靶向释放药物,具有良好的光热敏感性,该纳米微球在药物控释及药物载体等领域有广泛的应用前景。     

新型摇摆质量微陀螺的设计与制作(英文)

首先介绍了两种结构完全对称的高灵敏度的摇摆质量陀螺.设计并制作了一种对角驱动的新型摇摆质量微陀螺.利用硅的各向异性湿法腐蚀等MEMS体加工技术,简化了该微陀螺的制作工艺.该微结构的对称性、一致性和加工精度有很大改善,尤其是振动梁、激励部件和敏感部件等关键部件.详细阐述了该微陀螺的工作原理和结构设计,完成了微陀螺关键部件的制作和样机组装.利用NF公司的FRA 5087频率响应分析仪测试了样机大气下的振动模态,其中驱动频率为5.563 2 kHz,检测频率为5.553 4 kHz,频差为9.8 Hz,小于0.2%.利用频谱分析的方法测试了样机的哥氏力.测试结果表明这种摇摆质量微陀螺的设计与制作方法是可行的.     

基于ANSYS的新型压电陶瓷管驱动器的性能分析与研究

基于ANSYS有限元分析软件,结合压电铁电物理知识,对压电陶瓷管驱动器的性能进行分析与研究.首先对某进口压电陶瓷管进行ANSYS建模仿真,然后将分析结果与其出厂性能进行复核,最后对该驱动器进行了静态分析、谐响应分析等研究,获得了较为全面的驱动特性.     

微梳齿结构动态特性参量的光学测量与分析(英文)

光学测试方法属于非接触测量,目前已经成为MEMS动态测试领域的研究热点.为了实时检测梳齿式微结构驱动模态的谐振特性,由高速摄像机和显微镜组成的计算机微视觉光学测试系统和相关的视频分析软件被用于测量微梳齿结构的动态特性.利用这套微视觉光学测试系统,可以获得微梳齿结构驱动模态的位移响应曲线和幅频特性曲线,并可以进一步得到驱动模态的固有频率、品质因子、阻尼系数等参数.测得的结果与计算结果相比,一致性较好.     

光热激励的硅基双层微机械悬臂梁的特性研究及模拟优化

本文研究了硅基双层微机械悬臂梁在光热激励下的挠曲特性和频率特性 ,并利用建立的数学模型进行了模拟和优化。从而为新型传感器的研制提供了理论分析和优化设计的基础     

低温下Cu-Cu固体间界面热阻的激光光热法研究

以GM制冷机(20K/5W)作为冷源,用激光光热方法对低温下Cu-Cu固体接触界面热阻进行了测量。实验数据表明,在一定的压力(3.0 kPa)和温度范围(20~120 K)内,Cu-Cu接触界面热阻从2.445×10-2m2.K/W减小至3.022×10-3m2.K/W,同时,在一定的温度(80 K)和压力范围(3.0 kPa~0.32 MPa)内,界面热阻从5.547×10-3m2.K/W减小至2.876×10-4m2.K/W。从微尺度的角度对该变化规律进行了机理分析。     

溶胶-凝胶法制作PZT微驱动器的研究

采用溶胶-凝胶法(Sol-gel)制备了PZT压电薄膜,利用PZT的压电效应制作以PZT薄膜为驱动的V型阀微驱动器.针对微驱动器的关键结构驱动膜,探索了Si/SiO2/Ti/Au/PZT/Cr/Au多层驱动膜结构制备方法,解决了在硅基底上制备PZT薄膜的问题,同时详细探讨了硅各向异性刻蚀微驱动器的关键部件驱动腔、单向阀的工艺,解决了集成制作的V型阀微驱动器的关键工艺问题,并通过SEM照片对V型阀和多层驱动膜进行了表征.研究结果表明,采用MEMS与IC技术结合的方法成功地完成了微驱动器的研制,得到的驱动腔硅杯平坦均匀.在V型阀微驱动器整体设计中需要的硅片数目少,降低了器件的复杂性,可以满足低功耗、小型化和批量生产的要求.     

Photothermal therapy by using titanium oxide nanoparticles

The photothermal therapy (PTT) technique is regarded as a promising method for cancer treatment. However, one of the obstacles preventing its clinical application is the non-degradability and biotoxicity of the existing heavy-metal and carbon-based therapeutic agents. Therefore, a PTT material with a high photothermal efficiency, low toxicity, and good biocompatibility is urgently wanted. Herein, we report a titanium oxide-based therapeutic agent with a high efficacy and low toxicity for the PTT process. We demonstrated that Magnéli-phase Ti₈O₁₅ nanoparticles fabricated by the arc-melting method exhibit >98% absorption of near infrared light and a superior photothermal therapy effect in the in vivo mouse model. The Ti₈O₁₅ nanoparticle PTT material also shows a good biocompatibility and biosafety. Our study reveals Magnéli-phase titanium oxide as a new family of PTT agents and introduces new applications of titanium oxides for photothermal conversion.

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Absolute Measurement of Thermophysical and Optical Thin-Film Properties by Photothermal Methods for the Investigation of Laser Damage

Perspectives and limits of the application of the photothermal technique are given for the measurement of absorption, thermal, and thermoelastic properties in thin films. The peculiarities of this technique in the frequency and time domains are discussed in some detail, and selected important results with respect to laser damage studies in optical coatings are pointed out. Emphasis is placed on the absolute measurement of both optical and thermophysical properties in dielectric materials in thin-film form and, also, on the influence of both absorption and changed thermal properties in thin films on their thermally induced laser damage resistance.     

A Novel Comparative Photothermal Method for Measuring Thermal Diffusivity

A novel comparative method has been developed at the National Physical Laboratory (NPL) to measure the thermal diffusivity of semi-infinite samples without a priori knowledge of the boundary conditions. It is based on photothermal radiometry, and involves the detection of modulated thermal radiance from a target irradiated by a modulated, focused diode laser beam with a power of 1W. The technique exploits the fact that the frequency response of the surface temperature modulation scales with thermal diffusivity for a given target geometry (this is a fundamental property of the heat diffusion equation). In the process two samples are measured, one of which is known, and the diffusivity of the second material is derived from scaling the results over frequency. Measurements on samples of platinum and Inconel have shown the validity of the methodology but also raised issues concerning the difficulty of accurate measurements due to surface coatings or roughness.Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22--27, 2003, Boulder, Colorado, U.S.A.     

Photothermal deflection in a supercritical fluid

Photothermal deflection is among the most sensitive techniques available for the measurement of small, localized heating, such as that from the absorption of a focused laser beam in the bulk or surface of a material. A thin optical probe beam is deflected by the refractive-index gradients arising from the heating, and the size of the deflection provides the measure of the heating. We describe the use of a critical fluid to enhance the sensitivity of the technique by at least 10³. The diverging coefficient of thermal expansion of a pure fluid near the gas-liquid critical point gives this dramatic enhancement when used as a sensing fluid. With sensitivity calculations and measurements in supercritical xenon,T _c16.7C, we show that the noise floor of our apparatus when used for surface absorption measurements corresponds to a fractional power absorbed ofP _absorbed/P _incident=10^–10, while the noise floor for bulk measurements corresponds to an absorption coefficient=10^–13 cm^–1. We report the first measurements of the surface absorption of superpolished surfaces of sapphire and fused quartz,P _a/P _i2×10^–5, and the first measurements of the bulk absorption in xenon,2×10^–6 cm^–1. We also show how the present work fits into the current status of absorption measurement techniques and describe the effects of the peculiar properties of critical fluids on the execution of photothermal deflection measurements.     

Increase in Generation of Poly-Crystalline Silicon by Atmospheric Pressure Plasma-Assisted Excimer Laser Annealing

In this work, a novel atmospheric pressure plasma-assisted excimer laser annealing method for increasing the generation efficiency of poly-crystalline silicon from amorphous silicon layers is presented. Here, both the plasma and the laser propagate coaxially in order to generate energetic synergies. The influence of different process gases and plasma discharge modes as well as the working distance were investigated. Depending on the particularly applied plasma, the crystalline area was increased by a factor of approx. 1.1 to 1.9, where the highest efficiency was observed when introducing an argon plasma beam to the annealing process.     

Photothermal Depth Profiling by Thermal Wave Backscattering and Genetic Algorithms

Photothermal depth profiling is usually applied to inhomogeneous materials to localize the optical inhomogeneity or retrieve the thermal effusivity depth profile by simply monitoring the photothermal signal after the pump beam excitation. In this paper the different kinds of inverse problems related to photothermal depth profiling are discussed, and the solutions given by thermal wave backscattering (TWBS) and genetic algorithms (GAs) are compared. Finally, the different performances and limits of validity on known linear profiles are compared. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27 2003, Boulder, Colorado, U.S.A.     

Thin-Film Thermophysical Property Characterization by Scanning Laser Thermoelectric Microscope

This work presents a scanning laser-based thermal diffusivity measurement technique for thin films as well as for bulk materials. In this technique, a modulated laser beam is focused through a transparent substrate onto the film–substrate interface. The generated thermal wave is detected using a fast-responding thermocouple formed between the sample surface and the tip of a sharp probe. By scanning the laser beam around the thermocouple, the amplitude and phase distributions of the thermal wave are obtained with micrometer resolution. The thermal diffusivity of the film is determined by fitting the obtained phase signal with a three-dimensional heat conduction model. Experimental results are presented for a 150-nm gold film evaporated on a glass substrate.