In order to realize the automatic measurement of the particle circumference,a method of measuring particle cir-cumference with digital holography imaging is proposed. The basic theory of digital holography imaging is introduced. The struc-ture chart of the experimental device is given,and the autofocus algorithm for holography reconstruction is studied in depth. An improved autofocus algorithm based on wavelet transform is proposed. The specific method to measure the particle circumference is given on the basis of image segmentation of the holography reconstructed image. The experimental results show that the mea-sured circumference of the marine plankton is 17.918 mm,and its relative error is 3.51%. The particle circumference measure-ment method can basically satisfy the requirements of the stability,high precision and strong anti-interference for particle cir-cumference measurement,and has the important referential significance for the study on measurement of the other particle mor-phological characteristic parameters.%为了实现粒子周长的自动测量,提出一种利用数字全息成像测量粒子周长的方法.首先,介绍了数字全息成像的基本理论.接着,给出了实验装置的结构图,并对全息再现中的自动聚焦算法进行深入研究,提出一种改进的基于小波变换的自动聚焦算法.最后,在全息再现像图像分割的基础上给出粒子周长测量的具体方法.实验结果表明,测量的海洋浮游生物周长尺寸为17.918 mm,相对误差为3.51%.这种粒子周长测量方法基本满足粒子周长测量的稳定可靠、精度高、抗干扰能力强等要求,对其他粒子形态特征参数的测量研究也具有重要的借鉴意义.
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