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遥感器在轨绝对辐射定标能够实时评价传感器本身的辐射响应特性,及时发现并正确纠正传感器辐射响应变化。以恒星观测数据作为辐射定标参考源,点扩散效应使探测系统所接收的像与实际点光源分布存在较大差异。因此,要从获得的像中还原出点目标真实情况,就必须知道探测系统的点扩散函数。以高斯函数模拟系统点扩散函数,采用最小二乘法求解点目标相对于瞬时视场偏移,并提出了亚像元尺度上求解系统点扩散函数的新方法。模拟实验结果表明:该方法对点扩散函数分布计算精度较高(优于0.01%),且当探测系统能量集中度低于77%(MTF0.5<0.37)时,以恒星为目标的在轨绝对辐射定标方法可以满足5%的精度要求。
Remote sensor on-orbit radiation calibration can be real-time evaluation of the sensor’s radiation response characteristics, timely detection and correct correction of sensor radiation response changes. Stellar observational data is used as the reference source of radiation calibration. The point spread effect makes the images received by the detection system have a big difference with the actual point source distribution. Therefore, to retrieve the real situation of the point target from the obtained image, we must know the point spread function of the detection system. The Gaussian function is used to simulate the point spread function of the system. The least square method is used to solve the point-target offset relative to the instantaneous field of view. A new method to solve the system point spread function at the sub-pixel scale is proposed. The simulation results show that the proposed method has a high accuracy (better than 0.01%) for the distribution of point spread functions, and when the energy concentration of the detection system is less than 77% (MTF0.5 <0.37), the orbit Absolute radiation calibration method to meet the accuracy requirements of 5%.