基于多元正态分布的飞秒激光烧蚀光斑质心提取

飞秒激光在加工单晶硅过程中伴随着等离子体衍生发光现象,并以激光光斑形式表现出来,激光烧蚀效果受激光脉冲能量、光学设置、材料特性、环境参数等因素的影响,参数的选择是实现理想加工的关键,由此引入光斑质心的提取,研究光斑的变化规律以提高加工精度的目的。常用的质心提取算法有灰度质心法、高斯曲面拟合法等,但由于受到噪声的影响,光斑的灰度峰值可能发生偏差,提取的质心同真实质心相比误差较大,由此引入多元正态分布,在多个方向拟合高斯曲面,通过极大似然法估计质心,在精度方面得到了很大的改善。

Centroid extraction of femtosecond laser ablation spot based on multiple normal distribution

In the process of monocrystalline silicon processing,femtosecond laser is accompanied by plasma-derived luminescence,which is shown in the form of laser spot.Laser ablation effect is affected by laser pulse energy,optical setting,material properties and environmental parameters.The selection of parameters is the key to realize the ideal machining,so the paper introduces the extraction of the centroid of the spot and studies the variation rule of the spot to improve the machining precision.Commonly used centroid extraction algorithm are gray mass center method,gauss curved surface fitting and so on.However,due to the influence of noise,the light gray peak deviations may occur,and the extracted center of mass has a larger error compared with the real center of mass,thus introducing the multivariate normal distribution and fitting Gaussian surface in multiple directions and estimating centroid by maximum likelihood method,the accuracy is greatly improved.