Curved CMOS sensors, a reality: performance and status of on-going instrumental projects

Abstract

Curved and freeform sensors are now a reality and are about to become very beneficial for wide field imaging system. By directly correcting the field curvature of imagers and spectrographs in the focal surface, curved sensors allow to get rid of one third to half of the optics. This leads to a reduction of the volume and mass of the instruments, simplification of the optics prescriptions, while drastically improving the image quality. The ERC-ICARUS team and the SME CURVE developed a nondestructive, high quality shaping process. This paper provides details on the electro-performance of curved and freeform CMOS sensors made in house. We will also present results on the curvature and shape quality of these sensors and talk about future developments for astronomical instruments such as rovers cameras and spectrographs. We will describe the goals and the development of projects using curved sensors, that are today considered as technological demonstrators for the next five years. We will browse on-going projects that consider using curved sensors as a base line, such as CASTLE (wide field telescope) for Calar Alto or BlueMUSE (spectrograph) for the Very Large Telescope. Optical designs and specifications for the focal surfaces are presented, and compared to the existing performance. We will also detail our proposition to the ESA Space Weather Department of a design for a wide field/curved-sensor-based UV camera dedicated to in-orbit survey of Aurora and electromagnetic storms.