摘要
为了减小由于同轴数字全息系统的较大焦深而导致粒子的轴向深度定位具有的不确定性,本文提出了一种用于粒子轴向精确定位的基于最大梯度的自动聚焦算法。自动聚焦算法对包含粒子的对焦窗口中求出任意可能方向的梯度,比较后得到最大的梯度,利用最大的梯度作为最后的结果,其它的则丢弃。同时,考虑到自动聚焦算法的精确度和算法的稳定性,再引入阈值参数,利用这个阈值可以很好地滤除粒子再现像中的背景信息和噪声带来的干扰。经实验表明,该算法具有较好的单峰性和稳定性。
Due to the Depth of Focus （DOF） which is tens of times more than particle diameter in digital in-line Fresnel holography system, resolution of particle axial position is low and uncertain. In order to reduce the impact of DOF, an auto-focusing algorithm for accurate location of particle was proposed based on the most gradient. In the focus window containing particle, the gradients in all possible directions were calculated. Then, all of the possible gradients were compared, and the largest gradient was chosen as the result. At the same time, in order to improve the precision and stability of auto-focusing algorithm, another threshold parameter was introduced to eliminate the interference caused by background information and noise. Through experiments, we find out that the auto-focusing algorithm has the strong single peak feature and good stability.
出处
《光电工程》
CAS
CSCD
北大核心
2009年第9期82-86,共5页
Opto-Electronic Engineering
基金
上海市教委发展基金资助项目(05LZ12)
关键词
数字全息
粒子轴向定位
自动聚焦
焦深
digital holography
axial location ofparticle
auto-focusing
focus depth
