一种基于偏振光干涉的原子力显微镜测头的研究

为了提高测头的抗干扰能力,达到较高的分辨率,设计了一种基于偏振光干涉原理的原子力显微镜测头。该测头采用偏振光干涉式方法探测针尖的位移,可提高测头的灵敏度。分析了测头设计中焦点聚焦在探针悬臂梁上的可行性,并通过实验进行了验证。实验表明,Wollaston棱镜组可以有效地改变光程差。设计的共光路形式的Nomarski干涉仪光路,能够有效减小噪音的影响,并保证装置结构紧凑,适于实用。通过实验验证,此测头系统能够达到1nm的纵向分辨精度,为原子力显微镜测量技术提供有力支持。     

宽频段太赫兹辐射计高吸收率涂层的特性

为了对宽频段高吸收率太赫兹辐射计的特性进行表征,研究了吸收涂层材料的特性;对常见的吸波材料在太赫兹波段的吸收率进行仿真,探寻在太赫兹波段具有高吸收率的材料;将碳化硅与3M黑漆进行混合,以进一步提高涂层的吸收率,并通过仿真调整涂层内碳化硅颗粒的尺寸;根据仿真结果制备混合涂层,利用太赫兹时域光谱仪对混合涂层样品进行测量。结果表明:该混合涂层样品的光谱吸收率大于0.99,与仿真结果基本吻合。     

红外检测技术在古玉鉴定中的应用

系统介绍了古玉器鉴定中常用的红外光谱测试方法,其中包括溴化钾压片法、镜面反射法、漫反射法和红外显微镜法.说明了各个方法在古玉器鉴定方面的应用,对比了各种测试方法的优缺点.针对玉石品种的识别、加工磨料残余的识别、古玉沁变物的识别以及蚀变与玉质的关系研究等问题,举例说明了红外光谱测试技术在玉石鉴定中的应用.     

Comparison of erosion mechanisms in different types of cavitation

A new cavitation erosion device producing vortex cavitation has been extensively used. A comparative study between various cavitation erosion situations was carried out to verify the ability of this vortex cavitation generator to produce realistic cavitation erosion with respect to that observed in hydraulic machinery.For this purpose, specimens of indium and α + β brass were subjected to different cavitation erosion situations in a Francis turbine model, a cavitation water tunnel, a vibratory cavitation device and our vortex cavitation generator. The surface deformation and the development of damage in exposed specimens were examined using scanning electron microscopy. In all cases, except for the vibratory cavitation device, the damage starts with the formation of isolated hollows and craters of similar morphologies and sizes, produced by collapse impingements. The accumulation of isolated damage distributed statistically over the specimens results in erosion. Meanwhile, for vibratory cavitation the damage is initially scattered uniformly over the specimen surface and develops progressively. In spite of this, the topographies of severely eroded surfaces in various types of cavitation did not present noticeable differences. However, transmission electron microscopy observations of subsurface microstructures in eroded specimens indicate the same arrangements of dislocations and the appearance of largescale deformation twins. Hardened superficial layers in specimens exposed to flow cavitation are thicker than those in vibratory cavitation, which leads to higher erosion rates.     

提高差拍法布里-珀罗干涉仪测量精度的研究

文章在中国计量科学研究院研制的差拍法布里-珀罗（F-P）干涉仪基础上,提出用密封干涉光路的真空系统方法,来消除空气折射率变化对测量结果的影响。研究了空气折射率变化对测量精度的影响关系,给出真空系统所需的真空度的估计式。并设计制作了适用于该系统的密封干涉光路的真空系统。     

TEM室法环天线校准系统建立及测量结果不确定度评定

横电磁波室法是9 kHz～30 MHz频段环天线校准中广泛采用的一种方法.环天线分为有源环天线和无源环天线两类,这两种天线的磁场天线系数在量值范围上差别大,对系统动态范围要求不同.根据这一特点,对两类环天线分别建立横电磁波室作为标准场的环天线校准系统,基于网络分析仪开展扫频测量.针对电磁兼容领域中常用的直径60 cm以...     

X射线环境辐射监测仪器校准方法的研究

环境辐射监测仪表作为微弱放射性监测计量器具,它的量值溯源是一个急需解决的问题.由于环境辐射剂量率低且电离信号微弱,故通常采用大体积电离室或者充压电离室进行测量.依托60 ～250 kV X射线空气比释动能基准电离室,在完成重过滤窄谱X射线辐射质空气比释动能绝对测量的基础上,通过逐级替代法完成大体积环境辐射监测仪器的校准...     

A quick deviation zone fitting in coordinate metrology of NURBS surfaces using principle component analysis

Evaluation of the tolerance zone using discrete measured points plays a critical role in today’s manufacturing, metrology, and many industrial applications. The deviation zone is typically evaluated using a fitting method that locates an ideal desired geometry corresponding to a set of measured points while a function of the Euclidean distances of the measured points to the ideal surface becomes minimum. This paper presents a quick and reliable algorithm called Dynamic Principle Component Alignment (DPCA) for fitting complex surfaces to the coordinate metrology measured points using the information that is dynamically generated by Principal Component Analysis (PCA) of the measurement data and the corresponding fitted geometry. The developed algorithm efficiently eliminates the necessity for applying commonly used optimization methods for the fitting (localization) process, which decreases the computational cost and uncertainty of the evaluation process. Moreover, DPCA is very reliable and practical in coordinate metrology with large data sets in processes such as laser scanning and other optical methods. The results show that the proposed methodology more accurately finds fitting parameters in comparison with the other commonly used methods while the computational cost is considerably reduced.     

A compilation of patents related to mechanical metrology standards and high-precision measurement of mechanical quantities

The paper aims to provide a source of information regarding the measurement of physical quantities, specifically those related to mechanical metrology. Since there is a lack of literature reviews referencing patents as a way of gathering useful information, we performed a systematic search for patents that could solve practical problems in this field. The methodology used focused on one of the most comprehensive patent database, Orbit.com, covering about 70,000,000 documents. This text gives a quick look at the fundamentals of the measurement literature and then points out the state-of-the-art concerning patents in the area of study. Additionally, data analysis shows the trends in the last five decades of patents about the subject. In total, 5686 documents are found and we compiled 10 examples of relevant patents for the quantities Length, Temperature and Mass, making this article a source of information for both scientific and non-scientific metrology community.     

Fault diagnosis in six-phase induction motor using a current trajectory mass center

This paper proposes a new methodology for diagnosing the occurrence of stator winding faults in the six-phase induction motor. The proposed approach uses the xy current trajectory mass center of the motor stator currents. The Park transform is applied to the acquired induction motor stator currents. This transformation allows obtaining specific patterns that are used to identify stator winding faults. For healthy motors, a single point in the xy-plane is obtained. However, for a motor with a stator winding fault a circle is obtained, whose radius is related with the severity of the fault. To identify these patterns an algorithm, entitled current trajectory mass center, was developed. A theoretical analysis of the six-phase motor in αβ and xy current coordinates, for healthy and stator fault operation modes, is also presented. In order to show the applicability of the proposed technique several simulation and experimental results are presented.