Optical design of high-resolution camera with large compression ratio

Abstract

Obtaining high spatial resolution remote sensing images has always been one of the goals pursued in the field of remote sensing imaging. When the angular resolution of the remote sensor is constant, the closer the imaging distance, the higher the spatial resolution. For the remote sensor, the ground sample distance (GSD) at the nadir is closely related to the orbital height. Generally, the lower the orbital height, the easier it is to achieve high spatial resolution. With the rapid development of the ion thruster, spacecraft attitude adjustment technology and heat-resistant and corrosion-resistant materials, the use of ultra-low orbits to deploy micro-satellite, for earth observation and network collaborative information exchange has become an important direction in the development of aerospace technology. Based on the analysis of the development overview of typical foreign low-orbit satellites, combined with the analysis of orbit characteristics, this article summarizes the requirements of low-orbital satellites for remote sensor optical system. To meet the specific requirements, through comparative analysis of existing commonly used optical system forms, a new V-shaped high compression ratio optical system form is proposed, which greatly compresses the axial distance, and the focal length/length ratio is close to 10:1. A design example is given. Its technical specifications are as follows: focal length 4285mm, field of view angle 1.2°, F Number 8, the spectral range is 0.45 microns to 0.8 microns, the MTF value in the full field of view and the full spectrum is greater than 0.32 at the Nyquist frequency (83lp/mm), and the relative distortion is less than one ten thousandth. The simulation analysis results show that the imaging quality of the new V-shaped high compression ratio optical system proposed in this article is close to the diffraction limit, and the processing and assembly tolerance requirements are moderate. The engineering of the optical system is highly achievable, and it can well meet the application needs of low orbit.