All-spherical telescope with extremely wide field of view.

An all-spherical catadioptic telescope with the angular field of view of several tens of degrees in diameter and spherical focal surface is proposed for the monitoring of large sky areas. We provide a few examples of such a system with the apertures up to 800 mm and the field of view 30° and 40° in diameter. The curvature of the focal surface is repaid by high performance of the telescope. In particular, the diameter of a circle that includes 80% of energy in the polychromatic image of a star is in the range 1.″4-1.″9 across the field of 30° size and 2.″2-2.″9 for the field of 40° size. Some ways of working with curved focal surfaces are discussed. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]