Optical system: in particular a telescope

Optical system comprising an optical device which is a sphericalbody or has a spherical shape and comprises a first spherical surface,a plurality of two-by-two adjacent blocks covering the first spherical surface, and at least one light-transparent filler substance contained in a spherical cavity of the optical device. The optical system comprises a curved focal plane surrounding the optical device and on which animage produced by the latter is focused, and a receiving device comprising a plurality of chambers
arranged at the curved focal plane. Each chamber comprises a field lens and a diaphragm arranged downstream of the field lens with respect ot thecentre of the optical device. The diaphragm has the centre on the optical axis of the field lens so that optical projection of thediaphragm ontothe optical device through the field lens defines a virtualdiaphragm extending into the optical device.