Optical design of spaceborne multi-waveband Earth Observation system

Researchers have made considerable progress in the development of Earth Observation (EO) technology since 1960s. EO satellites usually span a quite wide wave-band from visible to infrared light or even to microwave. In this paper, we propose an optical design on multi-waveband spaceborne EO system. The design scheme adopts a coaxial two-mirror optical system together, which is able to image into visible light, near-and mid-infrared light as well as hyper-spectral channels simultaneously by utilizing a beam split parallel glass plate. The initial configuration parameters of the system are resolved by the primary aberration theory. Then we optimize the aberration by ZEMAX, which is one of the most popular software of optical design in the world. The channels of mid-and near-infrared light make use of re-imaging method, which allows the exit pupil match with the cold baffle of detector. The primary mirror of this optical system is used for visible and infrared wavebands together whose aperture is 700mm. The visible field of view is 1.08°×1.08°, focal length is 6450mm; the mid-infrared field of view is 0.66°×0.66°, focal length is 1620mm; the near-infrared field of view is 0.34°×0.34°, focal length is 3310mm. Consequently, this optical design can combine visible light and infrared light together and shrink the weight and volume of the system, meanwhile guarantee the imaging quality to be always near to the diffraction limit.