数字全息显微中的自动聚焦  

Autofocus in digital holographic microscopy

作　　者：王华英[1] 王广俊[2,3] 王大勇[2] 苏清磊 张奇峰 

机构地区：[1]河北工程大学理学院,河北邯郸056038 [2]北京工业大学应用数理学院,北京100022 [3]河南省计量科学研究院,河南郑州450008

出　　处：《光电子．激光》2010年第8期1232-1236,共5页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金资助项目(60577029);河北省自然科学基金资助项目(F2008000750);河北省科技支撑计划资助项目(09277101D)

摘　　要：为实现快速、准确的自动聚焦,采用理论分析和实验验证相结合的方法,对显微数字全息自动聚焦所采用的数值重建算法、全息图零级谱滤除和聚焦评价函数等相关问题进行了研究。结果表明:菲涅耳变换重建算法完全可以用于数字全息自动聚焦中;全息图零级谱的滤除使得基于菲涅耳变换算法的自动聚焦过程无法实现;灰度方差函数、傅里叶频谱加权对数函数和标准偏差相关函数可以有效地用于显微数字全息数中的自动聚焦,其中傅里叶频谱对数函数计算时间最短,是首选的聚焦评价函数;利用再现像光场中部分区域作为聚焦判断依据,可以大大缩短自动聚焦时间。The basic problems of autofocus in digital holographic microscopy,such as numerical reconstruction algorithms,zero-order spectrum filtering of hologram and focusing evaluation functions,are studied by theoretical analysis and experimental verification.The results show that Fresnel transform algorithm can be used in digital holographic autofocus;zero-order spectrum filtering of hologram leads to unsuccessful focusing evaluation which is based on Fresnel transform algorithm;gray variance function,weighted Fourier spectrum logarithm function and standard deviation correlation function can be effectively applied in the autofocus of digital holographic microscopy.Among these functions,the Fourier spectrum logarithm function is the best focusing evaluation function due to its lowest time cost.Moreover,the focusing evaluation time can be shortened dramatically by using the part of the reconstructed image field as the focusing evaluation area.

关 键 词：全息 数字全息术 显微 自动聚焦 菲涅耳变换算法 

分 类 号：TB877[一般工业技术—摄影技术]