为使光焦度计对光斑质心计算时同时具备高精度和快速的速度，考虑到光焦度计中光斑可能存在变形、部分缺失或二次反射等问题，并且对光斑计算只需要其质心位置的参数，本文提出了一种适用于光焦度计的椭圆中心快速计算方法。该方法通过二值数学形态学提取光斑的边缘，再通过改进的 RANSAC方法去除错误的边缘点以进行椭圆拟合，最后根据拟合后的椭圆表达式的系数直接计算椭圆的中心坐标，即光斑的质心。实验结果表明，该椭圆中心计算方法在光焦度计的使用中同时具有较快的计算速度和 Hough变换一样高的精度 0.01D，适合实际应用。

A fast ellipse center computation algorithm is proposed for optical power-meter to make it highly-accurate and fast, considering that the spots of optical power-meter may be deformed, partial absent or double reflected and the goal of the spot calculation is just to obtain the centroid. The edge of the measured spot is obtained by bi-value morphology. With improved RANSAC method, the false edge points are eliminated for ellipse fitting. And the center of the ellipse, which is also the center of the measured spot, is directly calculated from the fitted coefficient of the ellipse. Experimental result shows that, when applied to optical power-meter, the proposed algorithm is fast and as accurate as the traditional Hough Transform – 0.01D and it is suitable for practical application.