基于巴特沃斯特征函数的数字全息聚焦成像  

Digital Holographic Focusing Imaging Based on Butterworth Feature Function

作　　者：张瑞轩 刘丙才 岳鑫 房鑫萌 王红军 朱学亮 田爱玲 Zhang Ruixuan;Liu Bingcai;Yue Xin;Fang Xinmeng;Wang Hongjun;Zhu Xueliang;Tian Ailing(Shaanxi Province Key Laboratory of Thin Films Technology and Optical Test,School of OptoElectronical Engineering,Xi’an Technological University,Xi’an 710021,Shaanxi,China)

机构地区：[1]西安工业大学光电工程学院陕西省薄膜技术与光学检测重点实验室,陕西西安710021

出　　处：《中国激光》2024年第13期214-223,共10页Chinese Journal of Lasers

基　　金：国防基础科研项目(JCKY2020426B009);陕西科技厅项目(2023-YBGY-006)。

摘　　要：全息干涉条纹与待测物体轮廓相互混叠,严重影响数字全息成像的聚焦效果。针对此问题,提出了一种基于巴特沃斯特征函数的数字全息显微聚焦成像技术。该技术通过优化巴特沃斯滤波算法中特征函数阶数以及截止频率,使其适应全息图频谱分布特征,有效阻挡低频通过,从而建立了可有效抑制全息干涉条纹的滤波模型;在此基础上,利用八邻域梯度算子,完成条纹抑制后全息图像的边缘检测,结合图像灰度梯度算法,完成自动聚焦。实验表明:相比未经处理的原全息图,经所提算法处理后计算得到的聚焦曲线更陡峭,灵敏度提升到原来的66.35倍左右,运行时间缩短了54.78%,可有效提升数字全息显微成像的检测准确性。Objective As we all know, in an ideal optical system, the object and image distances should satisfy the Gaussian formula in order to achieve clear imaging in the optical path. In digital holographic microscopy, clear imaging of the object's light field is required for phase reconstruction. As a result, how to accurately establish the location relationship between objects and images during image capture has become a focus of current research. As the degree of defocusing grows, the image's edge dispersion and brightness both grow, which can result in considerable disparities between defocused and focused photos. The focusing function determination is significantly hampered by holographic interference fringes, which are a component of the image information. Of these, the entire region shows high-frequency noise in both speckle and fringes, which significantly lowers the signal-to-noise ratio of the reconstructed image. Furthermore, it is challenging to identify the defocused image because conventional focusing mechanisms are typically noisesensitive. Therefore, the key to tackling this challenge is identifying an appropriate focused picture evaluation technique.Methods To address the impact of noise errors introduced by holographic interference fringes during the experimental procedure on determining the ideal focal point, this research offers a digital holographic microscopic focusing imaging approach. This technique creates an off-axis digital holographic microscopic focusing imaging experimental system using transmission technology, based on the Mach-Zehnder interference system. The object optical path is scanned on-axis using a high-precision piezoelectric nano displacement stage to produce three sets of hologram sequences: digital holographic microscopic images, microscopic imaging image sequence, and simulated defocused sequence images. The impact of different speckle noise and interference fringes on the experimental results is ascertained by means of comparative observation. To address this issue, we propose

关 键 词：全息 数字全息 条纹抑制 巴特沃斯低通滤波 自动聚焦 

分 类 号：O438.1[机械工程—光学工程]