Acta Optica Sinica, Vol. 39, Issue 12, 1228005 (2019)
Correction Method for Frame-Transfer Blurring Effect of Spaceborne Polarization Camera
Weng Jianwen1,2, Yuan Yinlin1,*, Zheng Xiaobing1, Kang Qing1, Tu Bihai1, Li Jianjun1, and Hong Jin1
- 1Key Laboratory of Optical Calibration and Characterization, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- 2University of Science and Technology of China, Hefei, Anhui 230026, China
The frame-transfer blurring effect is a key factor that affects the precision of polarization measurement accuracy of highlight-target imaging via a frame-transfer array CCD camera. To improve the precision of spaceborne polarization cameras, it is of great significance to carry out studies on the measurement and correction method of the frame-transfer blurring effect. Considering the GF-5 satellite directional polarization camera (DPC) as an example, this paper investigates the generation mechanism and features of the frame-transfer blurring effect. The frame-transfer blurring effect is divided into the response-difference type, which is unrelated to the light conditions, and the smear type, which depends on the light conditions. To correct the features of the frame-transfer blurring effect in on-orbit imaging by the DPC, two correction models are proposed: the correction model of smear frame-transfer blurring effect based on the matrix and dark line methods, and the correction model of response-difference frame-transfer blurring effect based on the dark current channel. Finally, the optimal correction sequence and the feasibility of correction by the response-difference and smear frame-transfer blurring effects are verified by an integrating sphere. Additionally, the correction accuracy of the frame-transfer blurring effect in the DPC on orbit is verified using sunlight. Experimental results show that the proposed method reduces the influence of the frame-transfer blurring effect in the DPC on the polarization measurement accuracy of highlight targets, such as high reflective cloud and solar flare, from 7.28% to 0.43%, satisfying the calibration requirement that the DPC polarization measurement accuracy is <2%.