利用反射式衍射光栅进行瞬态应变测量

介绍了利用反射式衍射光栅进行瞬态应变测量的方法,在一维细长杆中,通过测量杆未端的绝对速度,就可以算出动态应变和应变灵敏度系数K,文章对该方法进行了理论计算和实验结果分析,给出了结论和进一步研究方向。     

3D Strain Field Measurement by Correlation of Volume Images Using Scattered Light: Recording of Images and Choice of Marks

Abstract:  We have extended the Digital Image Correlation technique to the case in three dimensions. This new technique, allowing the full three-dimensional (3D) strain measurement in the bulk of a solid, needs volume images containing a 3D variation of the grey levels. Generally, volume images are obtained by X-ray computed tomography. In this paper, we present a procedure that is easier to implement and enables to generate volume image in transparent materials. The principle consists in the optical slicing of the specimen. To obtain a random distribution of grey levels within the volume image, we use the scattered light phenomenon induced by particles included in the specimen. The recording of 3D images by optical slicing is presented and the influence of different kinds of particles on the scattered light and on the accuracy of measurement is described. Through several tests involving rigid body displacements and a tensile test we show the performance of this technique and we evaluate the measurement error of displacement and strain components.     

利用散射光信息提高消光法粉尘浓度测量的精度

提出了一种消光洗的基础上结合散射光提高粉尘浓度测量精度的方法，介绍了利用计算机模拟计算的结果和初步的实验情况。结果表明应用此方法可望实现简单、快速和较准确的粉尘浓度在线实时测量。     

Determination of a Small Number of Particles from Photocount Distribution of Scattered Light

We suggest and verify a simple inverse solution to the problem of determining the number of scattering particles from deviations of the measured photocount statistics from Bose-Einstein statistics. We also demonstrate that the experimental data are well fitted either by the theoretical photocount distribution corresponding to the log-normal intensity probability distribution, or by the Polya-Aeppli distribution.     

Measurement of Instantaneous Fluid Temperature and Two Fluid Velocity Components Using Hot-Wire Anemometers

Hot-wire anemometers, when used in a nonisothermal flow field, respond to both fluid temperature and fluid velocity fluctuations, even when operating conditions are selected to minimize the response to one of the stimuli. Use of a two-or three-wire array for the simultaneous measurement of temperature and velocity fluctuations and their mutual statistics has been shown to lead to significant errors, if, as is general practice, the approximate sensor responses are assumed to be ideal responses. An extension of the traditional techniques is described which eliminates this major source of error but still retains the simplicity of signal processing of the earlier methods.     

Measurement of Steep Surfaces Using White Light Interferometry

Abstract:  Scanning white light interferometry (SWLI) is an increasingly popular method to measure the surface profile of miniature components. Although it is tolerant to step changes in profile, its capability to measure the large surface gradients that are characteristic of high-aspect-ratio surfaces is limited. This is in part due to the numerical aperture of the objective lens which restricts the spatial frequency content of both the illumination and recorded fields. More fundamentally, though, SWLI instrumentation neglects the effects of multiple scattering and assumes that the field which illuminates the object is that which would be present if the object were absent. Although this is a reasonable approximation for slowly varying surfaces, it is generally not true for those with steep gradients. In this paper the 3D theory of SWLI is presented and the approximations made by current instrumentation are discussed in this context. Using finite element methods (FEM), SWLI interferograms are calculated, for the cases of 2D Silicon V-grooves and step artefacts, and the effects of multiple scattering are illustrated. Methods to improve the capability of SWLI to measure large surface gradients, first by tilting the sample and subsequently by using an iterative FEM model to provide improved estimates of the illuminating conditions are introduced.     

激光靶散射光观测镜杂散光抑制研究

分析了系统杂散光的来源,得出非成像光束对系统影响较大、平板玻璃窗产生的鬼像不容忽视的结论.针对传统作图法设计遮光罩的针对性不强,且追迹不同入射角的光线繁琐、容易遗漏的问题,本文提出一种逆向追迹法,依据光的可逆性,在像面处设置点阵面光源,每一点都发出充满系统孔径的光束,在物面设置足够大的探测面,使之有充足的余量记录所有到达物方的光线,利用该方法可以在探测面上直观她区分出非成像杂散光.有针对性地设计了具有特殊要求的内外遮光罩,并对遮光效果进行了软件模拟.     

用相位差分和Wigner分布估计信号瞬时频率

时变信号瞬时频率的测量有许多重要的应用。例如,在地震勘探、雷达、声纳、通信、生物医学中,瞬时频率是一些物理现象的很好描述。Wigner分布是时,频信号分析的有效工具。本文阐述了信号瞬时频率的概念及其定义。论述了用相位差分和用Wigner分布估计瞬时频率的方法。论证了Wigner分布峰值检测可以为高信噪比下线性调频信号提供最佳估计。     

多角度动态光散射法的纳米颗粒精确测量

基于动态光散射原理,采用自主研发的多角度动态光散射装置,对纳米及亚微米颗粒粒径准确测量方法进行了探究。自研装置采用带有光阑组的精密入射光路设计,以及匹配液池及Beam-stop设计,极大提高了信噪比;同时避免了测量角度的互补方向上,由于样品池与空气界面折射率不同导致的反射光信号对有效信号的干扰。在此基础上,对不同浓度、粒径的聚苯乙烯(PS)颗粒溶液进行了测定及不确定度分析。结果表明,对同一粒径的PS颗粒,增加颗粒浓度时,多重散射首先发生于大、小测量角度,越接近90°,发生多重散射的浓度越高;随着粒径增大,受不可忽略的颗粒间相互作用的影响,粒径测量结果表现出了强烈的角度依赖性,甚至波动性。     

Measurement of Intraocular Optical Distances Using Partially Coherent Laser Light

Abstract

The application of partially coherent laser light to measure intraocular optical distances is discussed. In a first step the optical thickness of the retina at the macula and the optical length of the eye has been measured and a precision of ± 0·03 mm has been obtained. The results of a comparison with the acoustically determined eye length and first fundus profile measurements are presented.     

Spectrum of Scattered Light by an Ionized Two-level Atom

Abstract

The spectrum of scattered light by an ionized two-level atom is investigated. The ionization is considered as a damping out of the ordinary two-level system and its effect on the spectrum is extracted. Because of the ionization damping, the central peak in the spectrum changes significantly according to the parameters involved. For a large ionization damping, a central dip is observed; for a small ionization damping, an additional sharp peak appears on top of the central peak.     

VisualBasic与Matlab接口技术在曲线拟合中的应用

MatrixVB是VisualBasic与Matlab的接口,VB采用这个接口来驱动Matlab,使VB和Matlab实现无缝集成。在使用VB进行Windows编程的同时,充分发挥Matlab在图形处理,计算等方面的优势,通过对工程数据进行插值等方法来实现曲线的拟合,进行直观的图形化显示。并举例说明了几种曲线拟合方法在MatrixVB中的使用,及这几种方法的原理,优点和缺点。采用这种接口技术可以方便应用程序的开发和增强应用程序的处理能力,满足工程需要。     

Measurement of Water Jet Velocity Distribution Using Laser Velocimetry

A laser Doppler velocimetry technique has been implemented in this work to evaluate the water jet velocity distribution in water jet and abrasive water jet cutting applications. Knowledge of the water jet velocity is fundamental to determine the system cutting efficiency; in particular, it allows us to experimentally determine the specific performance of the orifices employed in the cutting process.      

An Absolute Light Scattering Photometer: II. Direct Determination of Scattered Light From Solutions

The light scattering photometer recently described in this journal by McIntyre and Doderer has been examined to determine its ability to measure the absolute scattering of liquids. The absolute scattering of polymer solutions was determined from transmission measurements and from two different transverse measurements. The experimental results are in good agreement. The variables of the photometric system were also analyzed and experimentally studied to determine its ability to measure absolute scattering of liquids under different geometrical arrangements.     

The Wigner Distribution Function of Two-dimensional Signals Coherent-optical Generation and Display

We introduce the Wigner distribution function (WDF) as a self-windowed complex spectrogram and suggest some methods for the optical generation of the WDF of two-dimensional signals. The resulting WDFs, since they are four-dimensional functions, are represented as sectional images displayed either in parallel or as temporal sequences. We give some experimental results for real-valued input signals obtained from different coherent-optical WDF processors.     

Some Observations on Scattered Light and Lyman Ghosts Given by Diffraction Gratings

A number of gratings from different ruling engines have been examined in a spectrograph for Lyman ghosts and scattered light. The distributions of light at the exit focus and the distributions of error over the grating surface are complex. The patterns observed give an insight into the cause of the ruling error and, in particular, errors which are repeated several times along a groove length are found to be important.     

光幕靶光能分布研究及改善

光幕靶靶面光能分布的均匀性是影响弹丸测速精度的一个重要因素.以单个发光二极管为基础,近似处理后,进行数学建模分析,用代数叠加法推导出整个靶面光能分布公式,从而可得出靶面内任意点的光能量大小.当弹丸穿过靶面内任意一点时,都会遮挡一定的光能量引起接收端光通量的变化.过靶位置的光能量大小和接收端光通量变化大小成正比关系,从而导出靶面内不同位置和接收灵敏度的对应关系.对光幕靶进行一些改进以获得更均匀的光幕,提高弹丸测速精度.实验结果验证了理论的正确性和光幕靶改进的有效性.     

关于3D立体影像显示的双色眼镜方法——对《3D立体影像显示方法丛谈》的补充诠释

本文在概述3D立体显示的传统双色眼镜方法的基础上,介绍了一种新近面世的能显示色彩的双色眼镜方法——ColorCode 3D方法。     

逆反射光场光能分布

用统计的理论对逆反射光场的能量分布规律进行了研究,推导出光场能量的分布呈高斯分布,并借助于计算机仿真的方法找出了高斯分布参数σ与发散角、工作距离之间的关系。最后,采用ＣＣＤ图象传感器扫描测量逆反射光场,对实测数据进行随机样本分析,在实验中证明了理论分析的正确性。     

CCD实时图像采集处理系统测量光场相干性

本文描述了用CCD摄像机及DIP图像处理系统在双频光栅剪切干涉光路中测量光场相干性的原理和实测结果,以及讨论实验光路中逶镜非准直因素对测量结果的影响。