Research On The Space Target Measuring Optical System With High Precision And Large Field Of View

With the rapid development of space technology,the number of space targets in space,such as spacecraft and space debris,has increased exponentially,which greatly increases the probability of collisions between space targets.Therefore,precise measurement of space targets in a wide area to avoid collisions between space targets is one of the urgent problems to be solved today.However,traditional space cameras cannot meet the measurement requirements of high precision and large field of view(FOV).The combination of ultra-wide-angle,low-precision space cameras and smallfield-of-view high-precision space cameras can better solve this problem.Therefore,this paper mainly studies the key technologies,including the measurement accuracy of small field of view high-precision measurement camera and the design method of ultra wide angle low-precision measurement optical system.The main research contents of this paper are as follows:(1)Reducing the tolerance sensitivity of the optical system and improving the thermal stability of the focal length of the angle measuring optical system.First,in order to reduce the difficulty of processing and alignment of optical remote sensing camera,the tolerance sensitivity of optical system is studied in this paper.The method of controlling the surface curvature(absolute value)of each optical element in the optical system is proposed to reasonably distribute the optical power of each optical element,and realize the complementary of small aberration of optical system,so as to reduce the sensitivity of processing and alignment tolerance.Then,in order to reduce the influence of temperature on the angle measurement accuracy of the optical system,the thermal stability of the focal length of the optical system is studied in this paper.The method of matching the positive and negative lenses of different materials with the mechanical structure materials is proposed to improve the thermal stability of the optical system's focal length.Finally,the optical system is designed by using the above two methods.The design examples and analysis results show that the effect of the design method proposed in this paper is very significant.(2)Research on the method of efficiently calibrating angle measuring optical remote sensing camera using two-dimensional(2D)Dammann grating.First,the design principle and diffraction characteristics of the 2D Dammann grating are analyzed.Combined with the parameters of the camera to be calibrated,a 2D Dammann grating with a diffraction beam of 23×23 is designed and manufactured.Then,the highefficiency calibration optical path of the angle measuring optical remote sensing camera is built using the processed 2D Dammann grating,and the experimental data are collected and processed.The analysis results show that the angle measurement accuracy of the single star after the calibration of the camera is better than 6 ".Finally,in order to verify the angle measurement accuracy of the calibrated camera,an outfield star observation experiment is carried out on the angle measuring optical remote sensing camera.The outfield star observation shows that the probability of the angle measurement accuracy of the camera after calibration is better than 4" is greater than90%(joint calculation accuracy of multi stars),which verifies the feasibility of the highefficiency calibration method proposed in this paper.(3)Design method research on panoramic annular angle measuring optical system with ultra-wide angle and small blind area.First of all,the imaging principle of the traditional panoramic annular lens(PAL)is analyzed theoretically.Based on the imaging principle of the traditional PAL,a method is proposed to replace the traditional panoramic annular head unit(PAHU)with the reflective PAHU to reduce the central blind area of the optical system.Then,the mathematical model of the initial structure calculation method of the reflective PAHU is established,and the relative illumination of the optical system in the full FOV can be improved by using the aperture Coma.Finally,using the design method proposed in this paper,an ultrawide angle PAL with focal length of-2.0 mm,F number of 4 and FOV angle of(22°?120°)× 360° is designed.The design result shows that the blind area ratio is less than 3.67%,the distortion is less than 4%,and the relative illumination is good,the imaging quality is high and the structure is compact.The feasibility of the design method proposed in this paper is verified.