Noninterferometric topography measurements of fast moving surfaces

The topography of moving surfaces is recovered by noninterferometric measurements. The phase reconstruction is derived by measuring the intensities of a backscattered pulsed laser light and solving the transport intensity equation (TIE). The TIE is solved by expanding the phase into a series of Zernike polynomials, leading to a set of appropriate algebraic equations. This technique, which enables us to make a direct connection between experiments and the TIE, has been successfully tested in gas gun experiments. In particular, the topographies of a moving projectile and the free surface of a shocked target were recovered.     

Denoising in digital speckle pattern interferometry using fast discrete curvelet transform

In digital speckle pattern interferometry, the denoising of speckle fringe patterns is of vital importance for quantitative extraction of phase distribution. A filtering method of fast discrete curvelet transform based on weighted average thresholding technique is proposed in this paper for noise removal in speckle fringe patterns. Both computer-simulated and experimental digital speckle pattern interferometry fringe patterns are adopted to evaluate the performance of the proposed filtering method. In addition, a widely used and representative filtering method, windowed Fourier filter, is introduced for making a comparison and validation in the image processing effect, and the parameter of peak signal noise ratio is also used for assessment of denoising effect. It is shown from the filtered results that the filtering method of fast discrete curvelet transform is effecitve to remove speckle noises and simultaneously preserve fringe structure information.     

白光干涉测量法中蝠翼效应的模拟分析

为探索白光干涉仪在测量矩形台阶时的蝠翼效应误差,建立白光干涉虚拟测量模型.在模型中,考虑白光光源带宽和干涉物镜数值孔径以及圆孔衍射模型的影响,分析蝠翼效应与真实台阶高度、光源中心波长之间的关系.模拟结果表明当台阶高度差是λ0/4的奇数倍时会出现蝠翼效应,且越接近λ0/4的奇数倍,蝠翼效应越显著.关于对蝠翼误差的补偿,分...     

Position, velocity profile measurement of a moving body bymicrowave interferometry

A telemetric sensor that uses microwave interferometry to determine the velocity profile of a moving body following a known linear trajectory is proposed. By a slight modification of the design, it is possible to determine both the velocity profile and the distance to the trajectory. The principle of the method and the preliminary experiments carried out in the laboratory before extending the process to full-sized outdoor applications are described. The experimental results confirm the feasibility of the concept     

一种快速移动对象轨道聚类算法

针对已有轨道聚类(TRACLUS)算法的线段聚类模块需要对划分后的每条线段进行邻域查询的问题,将取样技术引入轨道聚类,提出一种快速移动对象轨道聚类(FTCS)算法。FTCS算法根据基于极大连通子图的合并原理,对核心线段的Eps邻域以及与该Eps邻域相重叠的所有轨道聚类进行合并,避免了TRACLUS算法中核心线段Eps邻域内线段的不必要邻域查询操作。在真实和合成轨道数据集上的大量实验结果表明,FTCS算法显著降低了邻域查询操作次数,在保持TRACLUS算法轨道聚类质量的同时,成倍提高了轨道聚类的时间效率。     

Analysis of capillary interferometry for measuring refractive indices of minute samples

A method of measuring the refractive indices of minute samples by analyzing capillary interferometry is introduced. With the interference theory of light, the intensity distribution of an interference fringe pattern formed by a cylindrical tube of a capillary is obtained, and the influence of some parameters on the fringes are discussed. The measurement accuracy and its relative problems are analyzed.     

快速背景重建的在线运动目标检测

为了能快速地从视频图像序列中创建可靠的背景图像,进而提取运动目标,文中提出了一种基于反馈信息的运动目标检测算法.首先提出了基于相邻帧信息和背景估计信息相融合的背景重建算法,保证了在视频场景改变时仍能迅速捕捉背景;还提出了基于一种在线Otsu法的运动目标检测,将相邻帧运动目标信息反馈到目标提取算法中,弥补传统Otsu法的不足;最后提出了对光线变化具有一定鲁棒性的背景估计算法.实验表明,该方法的重建速度快,准确率高,能满足实时检测的需要.     

Fringe modulation skewing effect in white-light vertical scanning interferometry

An interference fringe modulation skewing effect in white-light vertical scanning interferometry that can produce a batwings artifact in a step height measurement is described. The skewing occurs at a position on or close to the edge of a step in the sample under measurement when the step height is less than the coherence length of the light source used. A diffraction model is used to explain the effect.     

Numerical model estimating the capabilities and limitations of the fast Fourier transform technique in absolute interferometry

Anumerical model was developed to emulate the capabilities of systems performing noncontact absolute distance measurements. The model incorporates known methods to minimize signal processing and digital sampling errors and evaluates the accuracy limitations imposed by spectral peak isolation by using Harming, Blackman, and Gaussian windows in the fast Fourier transform technique. We applied this model to the specific case of measuring the relative lengths of a compound Michelson interferometer. By processing computer-simulated data through our model, we project the ultimate precision for ideal data, and data containing AM-FM noise. The precision is shown to be limited by nonlinearities in the laser scan.     

Application of real-time holographic interferometry for analyzing samples and imaging processes during flat-capillary electrophoresis

Application of the real-time holographic interferometry technique to the analysis of liquid samples by means of electrophoresis in a flat capillary is demonstrated.     

采用马氏模型的点状动目标快速检测方法

提出了一种视频序列图像中点状运动目标三维快速检测方法。该方法利用目标运动的时域连续性假设,将目标在相邻多帧上的位置状态模型化为二阶马尔可夫数据链;依照该模型采用沿轨迹集成的检测算法,克服了传统三维检测造成搜索次数巨大的弱点,同时也避免了二维投影检测带来的信噪比下降。理论分析和仿真试验表明,该检测方法能稳定地检测出信号杂波噪声比（SCNR）超过3的缓动点状运动目标,而且在采用5帧集成时计算量比传统的穷尽轨迹匹配检测减少100倍。     

On-line surveillance of a dynamic process by a moving system based on pulsed digital holographic interferometry

A method based on pulsed digital holographic interferometry for the measurement of dynamic deformations of a surface by using a moving system is presented. The measuring system may move with a speed of several meters per minute and can measure deformation of the surface with an accuracy of better than 50 nm. The deformation is obtained by comparison of the wavefronts recorded at different times with different laser pulses produced by a Nd:YAG laser. The effect due to the movement of the measuring system is compensated for by digital processing of the different holograms. The system is well suited for on-line surveillance of a dynamic process such as laser welding and friction stir welding. Experimental results are presented, and the advantages of the method are discussed.     

快速消费品配送服务标准化对策分析

本文探讨了快速消费品的特点及其配送服务的特点、配送服务存在的问题,并提出标准化解决方案。     

光学倍频影响激光外差干涉测量精度的机理

为了同时提高激光外差干涉测量的分辨力和精度,必须深入分析光学倍频对激光外差干涉测量精度的影响机理。在此基础上,建立了光学倍频相位测量模型,从理论上证明,光学倍频能够实现对激光外差干涉信号的细分,提高测量分辨力。光学倍频改变非线性误差的相位而使非线性误差减小,但同时改变了激光干涉多普勒频移的v/c平方项,使得残余累计误差增大。仿真结果表明,光学N倍频使非线性误差减小到原来的1/N,但使残余累计误差增大N2倍。因此,光学倍频仅适用于低速测量的场合。     

移动质量作用下轴向运动悬臂梁振动特性分析

将弹炮发射系统简化为移动质量作用下的轴向运动悬臂梁系统,推导了轴向运动梁的振动方程,采用修正的Galerkin法离散求解该偏微分方程,得到以模态坐标表示的二阶时变常微分方程组,通过Newmark-β法对方程组进行了求解。计算结果表明,移动质量载荷主要使梁的一阶模态受到激励,移动质量的大小和运动速度对悬臂梁的振动响应影响较大,在移动质量作用下梁的伸缩运动都处于不稳定状态;在移动质量脱离悬臂梁后,梁的轴向收缩运动使得梁的瞬时振动频率不断减小,振动位移逐渐衰减,而振动速度逐渐增大,梁的运动处于不稳定状态,伸展时梁的自由振动规律相反。     

The use of fast initial response features on the homogeneously weighted moving average chart with estimated parameters under the effect of measurement errors

Fast initial response (FIR) features are generally used to improve the sensitivity of memory-type control charts by shrinking time-varying control limits in the earlier stage of the monitoring regime. This paper incorporates FIR features to increase the sensitivity of the homogeneously weighted moving average (HWMA) monitoring schemes with and without measurement errors under constant as well as linearly increasing variance scenarios. The robustness and the performance of the HWMA monitoring schemes are investigated in terms of numerous run-length properties assuming that the underlying process parameters are known and unknown. It is found that the FIR features improves the performance of the HWMA monitoring scheme as compared to the standard no FIR feature HWMA scheme, and at the same time, it is observed that the simultaneous use of a recently proposed FIR feature and multiple measurements significantly reduces the negative effect of measurement errors. An illustrative example on the volume of milk in bottles is used to demonstrate a real-life application.     

Testing the effect of computer-generated hologram fabrication error in a cylindrical interferometry system

This paper presents a method of testing the effect of computer-generated hologram (CGH) fabrication error in a cylindrical interferometry system. An experimental system is developed for calibrating the effect of this error. In the calibrating system, a mirror with high surface accuracy is placed at the focal axis of the cylindrical wave. After transmitting through the CGH, the reflected cylindrical wave can be transformed into a plane wave again, and then the plane wave interferes with the reference plane wave. Finally, the double-pass transmitted wavefront of the CGH, representing the effect of the CGH fabrication error in the experimental system, is obtained by analyzing the interferogram. The mathematical model of misalignment aberration removal in the calibration system is described, and the feasibility is demonstrated via the simulation system established in Zemax. With the mathematical polynomial, most of the possible misalignment errors can be estimated with the least-squares fitting algorithm, and then the double-pass transmitted wavefront of the CGH can be obtained by subtracting the misalignment errors from the result extracted from the real experimental system. Compared to the standard double-pass transmitted wavefront given by Diffraction International Ltd., which manufactured the CGH used in the experimental system, the result is desirable. We conclude that the proposed method is effective in calibrating the effect of the CGH error in the cylindrical interferometry system for the measurement of cylindricity error.     

分布式MIMO声纳中运动目标参数快速估计

分布式MIMO声纳由于自身的优点而成为当前研究的热点,但常规的目标参数估计方法均存在着一定的缺陷,无法满足分布式MIMO声纳的要求.针对这种情况,本文提出一种适用于分布式多输入多输出(MIMO)声纳中使用单接收阵元的运动目标参数快速估计方法,给出了单接收阵元情况下的信号模型,提出了快速估计方法并给出了流程图,并通过数值...     

压电陶瓷的非线性特性校正研究

讨论了非线性对正弦相位调制Fabry-Perot(F-P)干涉术的影响.当用分块积分讨论相调F-P干涉术的输出光强,并作近似处理时,就可以给出类似的结果,所以把这种方法进一步推广到对相调F-P干涉术的研究中.同时提出了两种测量压电陶瓷非线性系数的方法,在实际测量得到的非线性系数基础上,完成`影响大小的数值计算和实验研究.最后证明提出,相调F-P干涉术的初相位应选择在π/4附近以及它可用于测量精细表面的粗糙度或其轮廓.