成像光斑中心精确定位是光栅衍射型超广角激光告警系统具有高定向准确度和高波长分辨能力的基础.本文分析了光栅衍射型超广角激光告警系统成像光斑特点.针对随激光入射角增大，系统成像光斑畸变为强度近似高斯分布倾斜光斑的问题，提出一种改进型高斯拟合法计算光斑中心，通过仿真模拟和实验测试研究了新方法的定位性能.模拟结果表明，高斯噪音标准差为0.01情况下，光斑长轴与x轴夹角由0°逐渐增大为90°过程中，本文方法的定位误差平均值小于0.005像素，误差标准差小于0.02像素.实验测试表明，实验图像经帧相减和高斯平滑滤波预处理后，光斑长轴与坐标轴方向一致时，本文方法与高斯拟合法的定位结果非常接近，明显优于灰度重心法.光斑倾斜时，本文方法求得的激光入射方向角的误差均值和标准差明显小于灰度重心法和普通高斯拟法.

The directional accuracy and wavelength resolution is highly dependent on the laser spot center location accuracy for the super wide-angle laser warning system based on grating diffraction. The spot features of this system was analyzed. As the imaged spots became tilt and its intensity was similar to Gaussian distribution with the laser arrival angle increasing, a new improved Gaussian fitting algorithm was proposed to locate the spot center. Then the accuracy and stability were verified by simulation and experiment test. The simulation results show that when the angle between long axis of imaged spot and x axis increases from 0° to 80° with standard error of Gaussian noise 0.01, mean errors and standard error of this method are smaller than 0.005 pixel and 0.02 pixel, respectively. The experiment test shows that after pre-process of frame subtraction and Gaussian filtering, results of the proposed method are close to weighted centroid and Gaussian fitting if the long axis of imaged spot is parallel to x or y axis, and both mean error and standard error for laser incoming direction of this proposed method are smaller than the other two methods when the imaged spot is tilted.