Optical design of a distributed zoom concentric multiscale meteorological instrument.

Abstract

A meteorological moderate resolution sensor requires large field of view (FOV) and low distortion imaging. At present, a fixed-focus camera combined with a whiskbroom scanning mechanism or a fixed-focus multi-camera combined with pushbroom scanning mechanism is being used. Owing to the fixed focal length of the camera, a large FOV causes the difference of imaging distance and ground imaging angle between the nadir point and the edge of the FOV to be significantly large, resulting in a large difference in the resolution between the nadir point and the edge of the FOV. The study proposes to simultaneously adopt a distributed zoom concentric multiscale system to realize a large FOV, low distortion, and high quality imaging to coordinate with different compensation lenses to achieve a different FOV corresponding to different focal lengths, where the resolution drop between the nadir point and the edge of the FOV is reduced. To ensure the same illumination of the entire FOV, the entire system possesses the same F# with different FOVs exhibiting different entrance pupil diameters. The study analyzes the principle of aberration compensation of a concentric multiscale system when both the FOV and entrance pupil diameter are changed and completes three groups of optical design of different focal lengths with uniform F#. The results indicate that the system has advantages of low distortion and high imaging quality in the entire FOV. Moreover, the resolution drop in the entire FOV is reduced to approximately 50% of the traditional design scheme. To verify the implementability of the system, a set of prototype manufacturing and imaging experiments are conducted to prove that the system has satisfactory implementability, and the imaging quality is also satisfactory.