Due to the increasing dimension, complexity and cost of the future astronomical surveys, new technologies enabling more compact and simpler systems are required. The development of curved detectors allows us to enhance the performances of the optical system used (telescope or astronomical instrument), while keeping the system more compact. This new technology allows one to have a compact and almost refractive elements-free telescope design, that is particularly suitable for ultra-low surface brightness (ULSB) observations, and a wide field of view that can be used for gravitational wave electro-magnetic counterparts search.
I will present the compact and almost fully reflective Schmidt telescope (CASTLE) aimed at testing the curved detector technologies. This telescope delivers a Point Spread Function (PSF) with extremely-compact wings, key factor for the detection of ULSB features in the sky. I present here the design and the first results obtained through full-system photon Monte Carlo simulations along with the ongoing activities on curved detectors.