散斑分数傅里叶联合变换相关测量研究

Research on the measurement of speckle displacement with joint fractional Fourier transform correlation

提出数字散斑联合变换分数相关测量方法,利用分数相关可以锐化相关峰的作用,在数字散斑联合变换相关运算中用分数傅里叶变换代替傅里叶变换,提高测量精度.通过对散斑图像进行相位调制,有效地解决了分数傅里叶变换的移变性带来的谱移问题.编程模拟和对拉伸试件位移场测量的结果表明,只要选择合适的分数傅里叶变换级次和相位调制函数,可以使相关峰的半宽度从4～5pixel锐化到仅1pixel,得到优于傅里叶变换相关的理想输出.

A method for the measurement of speckle displacement with joint fractional Fourier transform Correlation is presented. It performs fractional Fourier transform instead of Fourier transform in joint Fourier transform correlation to obtain better recognition peak. By using phase modulation to the speckle pattern,, the shifting problem of fractional domain spectrum from the shift-variant property of fractional Fourier transform is effectively solved. The results from simulation and measurement for the displacement field of object to be stretched indicate that this method is feasible. The semi-width of recognition peak is sharpened from 4-5pixels to lpixel and the Fractional Correlation peaks can be optimized by choosing the transform orders and phase modulation function.