A High-Precision Flat Field Method Based on Image Stitching for Short Wavelength Instruments

• DOI: 10.1007/s11207-020-1583-7
• Publication Date: 2020-01-21T09:02:50Z
• Authors: XingJun Gao; Bo Chen; LingPing He; Xin Zheng
• Keywords: Image stitching; Astron; Extreme ultraviolet; Robustness

We present a method to obtain a large-scale flat field using only small offsets. The method is derived from the Kuhn, Lin, and Loranz (KLL) algorithm (Publ. Astron. Soc. Pacific103, 1097, 1991), but combined with the image stitching technique. Due to complementary images, which optimize and replace the bad edges, the accuracy is better than 0.1 root mean square across the full field of view, and the pixel-level relative error is also better than 0.1%. Another significant advantage is that its small sampling interval provides a rapid sampling time, while maintaining a large-scale and high-precision flat field (beyond 95% proportion). We have proved its high efficiency and robustness by simulating a cosine and a Gaussian CCD response and comparing the results with the KLL algorithm. Finally, a visible non-uniform target experiment with a uniform response was performed to prepare for the upcoming solar X-ray Extreme Ultraviolet Imager (X-EUVI) instrument on the FengYun-3 (FY-3) weather satellite series.