针对多层靶丸X射线数字图像的成像原理和轮廓边缘进行了理论分析;推导了由靶丸边缘特征点确定靶丸圆心和半径的精确最小二乘拟合算法;对于不同类型(阶跃状或屋顶状)的靶丸图像边缘, 采用均化二阶微分算法或径向吸收强度最小二乘洛伦兹型拟合寻峰算法获取亚像素精度的靶丸圆周轮廓边缘数据;应用快速傅里叶变换算法对靶丸圆周轮廓数据进行分析, 获得了靶丸表面外轮廓或内轮廓模数-功率谱特征曲线。

Theoretical analysis of ICF shell X-ray radiography mechanism and the derived digital image’s profile edge forming is carried out. In order to determine the center and radius of the microsphere accurately, the least square fitting expressions with some characteristic points on the shell edge is deduced. For shell image edges of different types (step-shaped or roof-like), the average second-order derivative algorithm or the least square Lorentz fitting peak-finding algorithm of radial absorption intensity is used to obtain the ICF shells’ circumferential edge data with a sub-pixel accuracy. The power spectra curve as a function of the mode number of outer or inner profiles are also calculated by the application of fast Fourier transform to the circumferential profile data.