12 September 2017 An optimized knife-edge method for on-orbit MTF estimation of optical sensors using powell parameter fitting
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Abstract
On-orbit Modulation Transfer Function (MTF) is an important indicator to evaluate the performance of the optical remote sensors in a satellite. There are many methods to estimate MTF, such as pinhole method, slit method and so on. Among them, knife-edge method is quite efficient, easy-to-use and recommended in ISO12233 standard for the wholefrequency MTF curve acquisition. However, the accuracy of the algorithm is affected by Edge Spread Function (ESF) fitting accuracy significantly, which limits the range of application. So in this paper, an optimized knife-edge method using Powell algorithm is proposed to improve the ESF fitting precision. Fermi function model is the most popular ESF fitting model, yet it is vulnerable to the initial values of the parameters. Considering the characteristics of simple and fast convergence, Powell algorithm is applied to fit the accurate parameters adaptively with the insensitivity to the initial parameters. Numerical simulation results reveal the accuracy and robustness of the optimized algorithm under different SNR, edge direction and leaning angles conditions. Experimental results using images of the camera in ZY-3 satellite show that this method is more accurate than the standard knife-edge method of ISO12233 in MTF estimation.
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Lu Han, Kun Gao, Chen Gong, Zhenyu Zhu, Yue Guo, "An optimized knife-edge method for on-orbit MTF estimation of optical sensors using powell parameter fitting", Proc. SPIE 10395, Optics and Photonics for Information Processing XI, 1039506 (12 September 2017); doi: 10.1117/12.2271800; https://doi.org/10.1117/12.2271800
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