Optical design of Cassegrain system with wide field of view for spaceborne remote sensing application

The paper presents an efficient approach to design a Cassegrain optical system for spaceborne remote sensing. The optical system has a focal length of 1000mm, F number of 5.6, the range of spectral band 0.4~0.9μm, and field of view 3°, distortion smaller than 1%. The effect of central obscuration on the image quality in the optical reflective system design is analyzed. It provides proof for reasonable choose of obscuration ratio in optical system design. With the help of CODE V software, the final two designs are obtained by a simple and quick optimization step, the image quality of which reaches the diffraction limit. It is shown the second structure style is designed by making the surface of primary mirror in the Cassegrain system hyperbolic, adding two high order aspheric surfaces and removing two lenses from lens compensator, and therefore the second with the simpler structure, smaller size and lighter weight, comparing with the first structure style, can be used in spaceborne remote sensing.