Development of a Laser Speckle Interferometer to Measure Two-dimensional In-plane Vibration in Real-time Based on Fourier Transform with Electronic Circuit

基于电子电路傅里叶变换实时测量二维面内振动的激光散斑干涉仪的研制

基本信息

批准号：
13555063
负责人：
IWATSUKI Nobuyuki
金额：
$ 5.89万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Aiming to develop a high-performance vibrometer which can measure multi-dimensional displacement with high accuracy in real-time, a new laser speckle interferometer based on the quad aperture method with a phase detector of interference image using two-dimensional Fourier transform was proposed and was theoretically and experimentally examined. Analogue electronic circuit for two-dimensional Fourier transform was then designed. The results obtained are summarized as follows.(1)A prototype of a laser speckle interferometer with the quad aperture method was built. And by detecting a two-dimensional displacement of lattice type interference image with correlation method, a two-dimensional displacement of a target can be measured.(2)Two-dimensional Fourier transform of the lattice type interference image was theoretically derived. It was then revealed that displacement of the target was in proportion to the phase spectrum at the spatial frequency twice as high as the fundamental spatial frequency of interference image and that the calculation cost could be remarkably reduced in compare with that of the correlation method.(3)Experiments to measure the two-dimensional static displacement were carried out and then the factors to cause measuring error were discussed. It was revealed that the measuring error became smaller as the average visibility of the interference image was higher and as the phase variation in the image was smaller.(4)By selecting laser irradiation point so that the average visibility of the interference image is high and that the phase variation in the image is small, and by applying the 25 points median filter to the image, the measuring error becomes reduced.(5)An analogue electronic circuit which can calculate the phase of the fundamental frequency component of the interference image obtained with C-MOS image sensor according to two-dimensional Fourier Transform in real-time was designed.

旨在开发一种高性能振动仪，该振动仪可以实时测量具有高精度的多维位移，这是一种基于四维探测器的四维傅立叶图像的新激光斑点干涉仪，提出了二维傅立叶图像的相位探测器，并提出了理论上和实验检查。然后设计用于二维傅立叶变换的模拟电子电路。所获得的结果总结如下。（1）构建了用四孔径方法的激光斑点干涉仪的原型。通过检测使用相关方法的晶格类型干扰图像的二维位移，可以测量目标的二维位移。（2）理论上得出了晶格类型干涉图像的二维傅立叶傅立叶变换。然后发现，目标的位移与空间频率的相位频谱成比例，是干扰图像的基本空间频率的高两倍，并且与相关方法相比，可以显着降低计算成本。（3）实验以衡量二维静态位移的实验，然后将二维静态位移量化为误差。结果表明，由于干扰图像的平均可见性较高，并且图像的相位变化较小，（4）通过选择激光照射点，以使干扰图像的平均可见性很高，并且图像中的相位变化很小，并且通过将25点的基础过滤器应用于图像的频率（5）频率。设计了用C-MOS图像传感器根据二维傅立叶变换获得的干扰图像的实时。