Clermont L, Chouffart Q, Zhao Y
Centre Spatial de Liège, STAR Institute, Université de Liège, Avenue du Pré-Aily, 4031, Liège, Belgium.
Sci Rep. 2024 Aug 22;14(1):19490. doi: 10.1038/s41598-024-68802-z.
Space optical instruments play a pivotal role in enhancing our understanding of the universe and our planet, and are crucial in addressing the urgent challenges posed by climate change. In this context, stray light has emerged as a primary performance limitation. Originating from ghost reflections or scattering, it obscures essential details and introduces false information into images. With the demand for increasingly high-performing instruments, mitigation through hardware optimization is becoming insufficient. We are entering an era where future instruments require a stray light correction algorithm to meet user specifications, necessitating extensive on-ground calibration. This paper examines the Metop-3MI Earth observation instrument, which, with wide field of view, broad spectral range, and multi-polarization capabilities, epitomizes the challenges of stray light calibration and correction. A custom calibration apparatus was constructed to evaluate the complex stray light dependence on field-of-view, wavelength, and polarization. Data were processed, and stray light kernels database was derived, which then fed into a specially developed correction algorithm. Applied to the image of an extended scene, it effectively reduces stray light by a remarkable factor of 91. This achievement sets a new standard for low-stray-light instruments and provides a comprehensive case study for future missions.
空间光学仪器在增进我们对宇宙和地球的了解方面发挥着关键作用，对于应对气候变化带来的紧迫挑战也至关重要。在此背景下，杂散光已成为主要的性能限制因素。杂散光源于重影反射或散射，它会模糊关键细节并在图像中引入错误信息。随着对仪器性能要求越来越高，通过硬件优化来减轻杂散光影响已变得不够。我们正进入一个未来仪器需要杂散光校正算法来满足用户规格的时代，这就需要进行大量的地面校准。本文研究了Metop - 3MI地球观测仪器，该仪器具有宽视场、宽光谱范围和多极化能力，集中体现了杂散光校准和校正的挑战。构建了一个定制校准装置，以评估复杂的杂散光对视场、波长和极化的依赖性。对数据进行处理后，得出杂散光核数据库，然后将其输入专门开发的校正算法。将该算法应用于扩展场景的图像时，能有效将杂散光降低91%，这一成果为低杂散光仪器树立了新标杆，并为未来任务提供了全面的案例研究。
