中文说明：
该函数实现的是激光光斑中心检测。首先对光斑进行预处理，然后利用灰度重心法来计算得到光斑的中心坐标,最后利用MATLAB的绘图功能描绘出光斑中心位置的变化情况。
English Description：
This function is used to detect the center of laser spot. Firstly, the spot is preprocessed, and then the center coordinate of the spot is calculated by using the gray gravity center method. Finally, the change of the spot center position is described by using the drawing function of MATLAB.