The fast automatic interpretation of digital holographic interference fringes

Abstract

The holographic interference fringes recorded in the holography experiment often have many defects. The method put forward in this paper, which is based on the properties of Hough transform and Fourier transform, is an effective way to interpret the holographic interferogram of poor quality and can be used to count the number of the fuzzy linear interference fringes accurately. When interferogram is processed by Hough transform, the transformed fringes in Hough space will be convenient to count. After the Hough transform, the result is processed by Fourier transform for accurately calculating fringe number, the gray maximum, which demotes the period number of interference fringes, will be easily calculated out in the frequency domain. At first, in order to obtain accurate fringe number and avoid the noise influence, the interferogram is processed by the edge extraction of canny. Then the orientation of holographic interference fringes can be obtained by Hough transform and Fourier transform after the edge extraction result is processed. At last the original interferogram is processed by Hough transform and Fourier transform. This method can be used in the automatic interpretation of holographic interferogram, which are recorded in the holographic interferometry experiments for displacement measurement or deformation measurement. The holographic interference fringes have been successfully recognized and exactly counted. The experiments show that not only the method has avoided the influence of the uneven gray and the serious blur of fringes, but the test precision and efficiency of the digital holographic interferometry has also been greatly raised. The test result shows that the measure precision can be reached up to 1/100μm.