数字同轴全息对刀技术中微细铣刀的自动聚焦方法

Automatic Focusing Criterion Function for Digital Holograms of Micro Milling Tool

摘要:

数字同轴全息对刀技术中微细铣刀全息再现像的自动聚焦是实现高精度自动对刀的关键技术,其中聚焦评价函数是判别图像质量的依据。通过比较几种常用的聚焦评价函数的评价性能,探讨了数字全息自动对焦过程中刀具的成像特点以及适用的聚焦评价方法,发现小波变换聚焦评价函数能适应高精度聚焦的需要。针对自动调焦问题,提出一种分段递进搜索方法,将搜索过程分为两个过程:大步距粗调和小步距精调,分段搜索最优解。然后比较分析了所提搜索方法与经典的模拟退火算法和Levenberg-Marquardt算法的搜索性能。实验结果表明,所提分段递进搜索方法适用性更强,并通过计算机模拟实验进一步验证了其有效性。

Abstract:

The automatic focusing of the holographic reconstructed image of the micro-milling tool in the digital in-line holographic tool setting technology is the key technology for realizing high-precision automatic tool setting, and the focus evaluation function is the basis for discriminating image quality. In this paper, by comparing the performance of several commonly used focusing evaluation functions, the imaging characteristics of the tools in the digital holographic autofocus process and the applicable focusing evaluation method are discussed. Aiming at the problem of automatic focusing, a piecewise progressive search method is proposed, which divides the search process into two processes:coarse adjustment of large step and fine adjustment of small step, and piecewise search for the optimal solution. Then the performance of the proposed search method is compared with that of the classical simulated annealing algorithm and Levenberg-Marquardt algorithm. The experimental results show that the proposed piecewise progressive search method has better applicability, and the computer simulation experiment further verifies the effectiveness of the proposed method.