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Curved sensors enable a substantial simplification of optical systems and significant improvement of the image quality. Both lead to the reduction of the mass-volume budget of the instruments, simplify the manufacturing and shrink the integration time, resulting in a drop of the consolidated cost. The field curvature is an optical aberration describing the light going through an imager and producing an image on a portion of a sphere. This aberration is present in every single optical system and particularly in wide-angle imaging. Current solutions applied to correct the images imply the complexification of the instruments by using field flatteners, ie. more optics of complex shape, thus increasing the mass-volume and cost budget. The use of curved sensors helps overcoming these issues. It corrects the field curvature directly at the focal surface. For 10 years, the CNRS-LAM demonstrated, through theoretical studies and prototyping, that the use of curved sensors allows to remove 30 to 50 percent of the lenses count and drastically releases constraints in optical systems. I am currently leading a parametric study regarding the contribution of curved sensors for UV imaging system. This study is done through an imager aiming at observing aurora with a wide field of view (more than 60 degrees) in 130-138nm bandwidth with a signal to noise ratio higher than 10. The first main constraint in this project is to get a high transmissive system in FUV bandwidth. To address this problematic, the number of lenses must be reduced. However, reducing the number of lenses means reducing the number of degrees of freedom to correct the aberrations of such a wide field system. To maintain high optical performance, I have considered the use of curved and freeform sensors to correct the field curvature and astigmatism directly in focal surface. In this talk I will present the parametric study I have been leading on the design of this FUV imager. I will quantify the benefits of using curved and freeform sensors compared to flat sensor to keep high performance whilst reducing the number of lenses from 6 to 3 to increase the throughput by a factor 3.
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