COHERENCE MODULATED ACOUSTIC SPECKLE INTERFEROMETRY

相干调制声学散斑干涉仪

• 批准号: 1895553
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1895553
• 关键词: COHERENCE; MODULATED; ACOUSTIC; SPECKLE; INTERFEROMETRY

Sophisticated mines buried in the sea bed on littoralcoast lines pose a threat to any vessel in the vicinity.Their danger comes largely with their camouflage, astheir presence in the sand could easily be mistaken fora rock, coral or even man made material.Despite elo-quent seabed mapping techniques, it is difficult to detectsuch a mine without having a high probability of falsepositives.A method of characterising these objects inorder for detection to be made possible is devised anddetailed in this report.Speckle interferometry is an optical process that al-lows the analysis of an object's roughness.The tech-nique involves exposing the object to a laser, and if its re-flection scatters and interferes with itself, a characterisa-tion can be made on its surface texture.However, opticalmethods of identification are unreliable in ocean envi-ronments due to inhomogeneities in the medium.For ex-ample, small particles, fluctuations in density and salin-ity, or sea life.The technique is then translated into anacoustic context, where such inhomogeneities are lessof an obstacle.The idea is to send a sound wave froman underwater sounder to a target object and record itsreflection using a linear array of sensors.The variationin amplitude over the array, particularly the interferencepatterns due to the partial coherence of the signal, shouldallow a classification of the structure of the reflectingsurface.A challenge which is faced in the design of this tech-nique is determining the source signal required for thedistinction of given surfaces.For the classification offiner details on the object surface, a signal with a shapedspectrum may be necessary, for which the parametersneed to be investigated and determined.Further to this,there is the problem of developing a software model foracoustic surface reflections, particularly when the sur-face is irregular and the source has a complex spectralstructure.This document describes the plan of research for thisproject including the current work from which can bedrawn.This includes previous work done on the topicas a direct predecessor to the Ph.D. The plans are out-lined for developing the software tool, which will beimportant for much of the research, and designing thealgorithms for determining surface roughness from theinterferograms based on similar technologies used formapping.

埋在沿海海岸线海床上的复杂水雷对附近的任何船只构成威胁。它们的危险很大程度上来自于它们的伪装，因为它们在沙子中的存在很容易被误认为是岩石、珊瑚甚至人造物质。使用常见的海底测绘技术，很难在不出现高误报概率的情况下检测到此类水雷。设计了一种表征这些物体的方法，以便能够进行检测散斑干涉测量是一种光学过程，可以分析物体的粗糙度。该技术涉及将物体暴露在激光下，如果其反射散射并干扰自身，则表征可以在其表面纹理上进行识别。但是，由于介质的不均匀性，光学方法在海洋环境中识别并不可靠。例如，小颗粒、波动然后，该技术被转化为声学环境，在这种环境中，这种不均匀性不再是一个障碍。这个想法是将声波从水下探测器发送到目标物体，并使用线性阵列记录其反射阵列上幅度的变化，特别是由于信号的部分相干性而产生的干涉图案，应该可以对反射表面的结构进行分类。该技术的设计面临的挑战是确定区分给定表面所需的源信号。为了对物体表面的更精细细节进行分类，可能需要具有整形频谱的信号，为此需要研究和确定参数。除此之外，还存在开发问题声学表面反射的软件模型，特别是当表面不规则并且源具有复杂的频谱结构时。本文件描述了该项目的研究计划，包括可以从中得出的当前工作。这包括以前在主题是博士学位的直接前身。这些计划概述了开发软件工具（这对于大部分研究都很重要），以及设计基于形成映射的类似技术从干涉图确定表面粗糙度的算法。