Two-step focusing anamorphic catadioptric telescope and componentwise aberration compensations

Abstract

Aberration compensation with emphasis on the generalized spherical aberration components is discussed for plane-symmetric and anamorphic optical systems. A narrow field-of-view double-plane symmetric telescope objective containing reflective and refractive subsystems, which focus light separately in the two dimensions of the image plane, is introduced. Analytical derivation of the compensation rules is discussed for the telescope being composed of a Cassegrain-type cylindrical reflective subsystem and an economical refractive one that is determined by up to six essential parameters. Performance of a more advanced version of this telescope, which contains a less aberrative nine-parameter refractive subsystem, is studied using the ray-tracing simulator CODE~V. The telescopes of the introduced type provide two independent focal distances for the discussed focusings in the orthogonal dimensions allowing to set up a favorable field of view, and potentially can be used to achieve larger effective aperture area and resolution on a small spacecraft.