Space telescope designed for accurate measurements

Abstract

A modified version of the folded aplanatic Gregory telescope equipped with a spherical two-lens corrector is proposed for observations requiring a high signal-to-noise ratio. The basic telescope model has an aperture of 400 mm (f/3.0), its field of view is 3.0 degrees, the linear obscuration is 0.12, the distortion is less than 0.5%. The focal surface has a spherical shape; the achieving of a plane field requires an increase in the number of lenses in the corrector. The images of stars in the integrated wavelength range 0.35 - 1.0 mcm are close to the diffraction-limited ones (D_{80} = 5.9 - 8.2 mcm = 1.0 - 1.4 arc seconds). The system is free from direct background illumination; both the lens corrector and the light detector are protected from cosmic particles.