Optical design and development of a multichannel corrector for the 80cm Mezzocielo wide-field demonstrator

The Mezzocielo project is an innovative telescope is being designed to observe nearly the entire night sky simultaneously. It features a hollow sphere, made of spherical N-BK7 glass meniscus shell, filled with a transparent liquid that together acts as a light collector, focusing the incoming light to a multi-channel correcting system. The telescope covers an ultra-wide field of view of about 10,000 square degrees, managed by a multi-channel corrector architecture with approximately 900 channels. Each channel is equipped with a dedicated optical train and a CMOS detector. In this study, we present the optical design and iterative development of a corrector for an 80 cm on-sky demonstrator. The design process is driven by the need to balance image quality, light collection efficiency, detector sampling, manufacturability, and channel packing constraints. The current corrector design achieves a field of view of approximately 5◦ in diagonal across a spectral range of 500–800nm with a 360mm equivalent aperture, leading to approximately 45% of the 800mm diameter sphere. The optical assembly consists of field lenses, spherochromatism-correcting elements, and an objective group. Lens diameters, curvatures, and aspheric content are limited to ensure manufacturability and enable replication across adjacent channels.