EUV telescope for a Cubesat nanosatellite

This paper describes in detail a compact (2U format) telescope operating in the extreme ultraviolet range for studying the solar corona at a wavelength of 17.14 nm. The telescope objective has been built according to the Ritchey-Chretien scheme with the following parameters: effective focal length of 381.3 mm, field of view of 2 x 2 degrees, and angular resolution of 11 in. Reflective multilayer Al/Be coatings were used, having 55% reflectance and a 0.4 nm spectral bandwidth. The wavefront rms error is 30 nm. An interferometric technique for controlling the shapes of the substrates and for adjusting the optical system and detector of the telescope assembly is described in detail. (c) 2023 Optica Publishing Group