Research On Misalignment Correction Technology Of Large Aperture Telescope Optical System

With the increase of human space activities,space debris is increasing,which seriously threatens the safety of spacecraft.In order to effectively remove or evade space debris,it is necessary to accurately detect their size and orbit information.Ground-based optoelectronic telescopes are a key means for detecting space debris due to their high detection capabilities and long operating range.In order to improve the condensing ability and spatial resolution of the telescope,the aperture of the telescope continues to increase,and the difficulty of misalignment correction also increases.During the observation process of a large-aperture telescope,the imaging quality and observation accuracy of the optical system will decrease with the increase of the mirror misalignment error,which makes it impossible to accurately observe the space target.For this reason,misalignment correction is required to meet the observation requirements.This paper takes large aperture and wide field of view ground-based optoelectronic telescopes as the research object.This type of optical system is easy to be blocked by the detection optical element and its internal space is limited,making it difficult to place the detection optical element.To solve this problem,it is necessary to study an image quality detection method without adding detection optical elements and cooperate with the corresponding misalignment correction technology to realize the position misalignment correction of the optical system.The specific research work is as follows:1.According to the characteristics of the internal space limitation of the telescope optical system,the wavefront curvature sensor without field lens is studied.Since the detection optical element cannot be placed,it is realized by the direct measurement method,which solves the problem of space limitation and light blocking.The realization method of wavefront curvature sensor in the application of large-aperture and large-field telescope is analyzed.2.A sensitivity matrix method based on eigen coefficients is proposed to solve the misalignment of optical system.The Zernike coefficients obtained by the curvature sensor often use the Zernike polynomial fitting method,which requires the detector to be divided,which complicates the process of solving the offset.The eigenfunction method without zone detection is used to reconstruct the wavefront,and the eigen coefficient can describe the wave aberration.By analyzing the relationship between the eigen coefficient and the misalignment of the optical element,the sensitivity matrix model between the two is established,and the selection principle of eigen coefficient is given.3.The misalignment correction simulation of the 1 m coaxial three-mirror optical system is carried out.Because the sensitivity matrix of eigen coefficient of the system is ill-conditioned,combined with the decenter and tilt of the optical elements,which have the property of mutual compensation for aberrations,the grouping compensator method is selected for misalignment correction.The simulation results show that good image quality can be obtained.4.The misalignment solution experiment was carried out on a 1.8 m telescope,and the result shows that the eigen coefficient sensitivity matrix method has high accuracy,which lays a technical foundation for practical applications in larger-aperture telescopes.