Design Of Large Field Of View Pushover Optical System Based On Free-Form Surface

Since the 1970s,space optical remote sensors have gradually entered the fields of national defense and the national economy,and today the economy is developing rapidly.High-precision,high-resolution ground imaging and remote sensing technologies are in great demand in tourism,transportation,environmental monitoring,geographic mapping,and disaster prevention.The field of view of remote sensing optical systems has expanded from a few degrees to a dozen degrees or even dozens degrees,the resolution of the Geoelement is increased from several hundred meters to several tens meters or even several meters.In the case of certain ground target information,in order to obtain reliable information in a timely manner,multi-satellite orbiting and a high return period are required to increase the scanning width,and the optical system needs larger focal length and field of view.Traditional optical systems use area array detectors that take into account the fields of view in the meridional and sagittal directions.With the system's focal length increasing,the field of view cannot be effectively expanded.The off-axis push-broom optical system mainly considers meridian or sagittal direction.At the same time,based on the use of free-form surfaces,the system can effectively correct high-order aberrations caused by wide beams,astigmatism and coma caused by a large field of view,so the field of view can be increased while effective promoted the focal length.In this paper,a large field of view push-broom optical system based on free-form surface is designed.The initial structure of the optical system is obtained based on the third-order aberration theory.The initial structure is optimized using genetic algorithms,Finally,an aspheric off-axis three-reflection optical system with an entrance pupil diameter of 150 mm,a focal length of 1300 mm,and a field of view of 20°×2° was obtained.Using Monte Carlo tolerance analysis theory of sensitivity function,the assembly error analysis of the aspheric off-axis three-reflection optical system is completed.The differences in precision and processing of free-form optical elements are introduced.The Zernike freeform model is introduced to optimize the aspheric off-axis three-reflection optical system.The extended performance of the field of view and the clear aperture are explored under a certain focal length.Finally,The design of the free-form off-axis three-reflection optical system with an entrance pupil diameter of 162.5mm,a focal length of1300 mm,and a field of view of 35°×2° was completed.Tolerance analysis was completed using ZEMAX,and the optimized error analysis results of the optical system were given.Aiming at the design of long aspheric and free-form optical elements,according to the design method of aspheric mirror compensator with spherical aberration matching,the design of the compensator for large-aperture aspheric mirror detection is completed.Based on the digital holographic zero detection(CGH)method and the ray tracing method,the design of the CGH compensation plate for the free-form primary mirror is completed.ZEMAX-ZPL and MATLAB were used to simulate the CGH phase function and the binary grating ring zone to complete the design of the detection scheme.Finally,the ZEMAX was used to verify the correctness of the CGH.