基于二维各向异性高斯拟合评价探测相机的成像质量

为了定量评价探测相机的成像质量,提出用二维各向异性高斯函数拟合的方法来评价相机的成像效果。用探测相机采集星模拟器产生的无穷远处的点目标,形成在一定区域内的能量分布。以拟合后的高斯能量分布与原分布的相关度最大为判据,对此能量分布进行二维各向异性高斯拟合,得到其高斯半径、异化因子等参数;对拟合后的结果进行数值积分得到80%能量所占区域的大小。实验结果显示:相关度的引入,实现了背景阈值、异性因子的自动优化,减少了面阵探测器的噪声对测试结果的影响;而异性因子的引入,对像素相位误差的评估、光学系统像差对测试结果的影响,均可作为弥散斑测试定量确认的依据。测试实验显示:弥散斑等效面积圆直径测试重复性在"十"字工况吸收为0.15pixel,在"田"字工况下为0.19pixel。提出的方法完成了探测相机对点目标所成弥散斑的测定,很好地控制了探测相机的成像质量。

Assessment of image quality for spot-detecting camera with anisotropic Gaussian fitting

To evaluate quantitatively the image quality of a spot-detecting camera, a 2D anisotropic Gaussian fitting method was proposed. A spot-detecting camera was used to collect the infinity point target coming from a star simulator, and a certain area of energy distribution was obtained. Based on the correlation of the Gaussian energy distribution and the original distribution, this energy distribution was used in anisotropic Gaussian fitting to solve the parameters such as Gaussian radius and anisotropic factor. Then, the size of 80% of the energy was obtained by numerical integration. The experimental results show that the background threshold and anisotropic factor are optimized automatically and the influence of the noise on test results is reduced since the correlation is introduced. Moreover, the introduction of anisotropic factors, evaluation of pixel-phase error and the effect of optical system aberration on the imaging quality of the camera can be used as the testing condition criterion for defocused spots. The experimental results show that the repeatability of equivalent area circle diameter for the defocused spots is 0.15 pixel under the crisscross-shaped condition and that is 0.19 pixel under the farmland-shaped condition, respectively. The proposed method implements the defocused spot test by spot-detecting cameras, and also controls better imaging quality.