基于FFT的散斑干涉术测物体变形

Object deformation measurement based on FFT speckle pattern interferometry

在SPI测量变形物体三维位相的原理上,提出了用一个干涉图法,基于二维FFT实现了散斑干涉图三维位相测试的新方法。选用马赫-泽德干涉系统,用CCD分别接收物体变形前后的散斑图,将两幅散斑图相减可以得到变形物体的散斑干涉条纹图。应用MAT LAB软件编程对散斑干涉图进行二维FFT运算,获得变形物体的三维位相。由三维位相分布可以判读物体的三维变形,进而为后续分析物体的三维应力奠定基础。实验表明,该方法简单、速度快,精度可达到λ/10。

Based on the principle of measuring the 3D phase of deformation object with SPI,one step interference pattern method is proposed.And based on two-dimension FFT,a new method of measuring 3D phase of speckle interferogram is realized.Choosing Mach-Zehnder interference system and using CCD to receive the speckle pattern of the object before and after deformation respectively,the speckle pattern interference figure of a deformation object can be gotten by subtracting the two speckle pattern.Programming with MATLAB software to make Fast Fourier Transform of the speckle pattern interference figure,the 3D phase of the deformation object can be obtained.From the 3D phase distribution,3D object deformation can be detected and judged.That lays the foundation for further 3D stress analysis of the object.The experiment results show that the method is simple,fast and accurate.The precision can reach up to λ/10.