Research On The Technologies Of Active Optics For Large-aperture Segmented Optical/Infrared Telescope

With the rapid progress of modern astronomy,the requirements for the telescope’s detection capabilities are constantly increasing,and the requirements for the telescope’s aperture are also increasing dramatically.Affected by factors such as mirror blank manufacturing,optical processing,transportation and adjustment,large telescopes larger than 8m can only be realized by segmented mirror technology.For large segmented primary mirror telescopes,active optical co-phase maintenance and cophasing detection of segmented mirrors are the key points and difficulties.Keep co-phasing of segmented mirrors.After co-phased of the segmented mirrors is achieved by optical methods,the co-phase state among the segments is destroyed by the influence of gravity,wind load,heat,vibration and other factors.The active optical system monitors the relative position and attitude changes between adjacent two segments through the edge sensors,and then the active optical control system calculates the compensation amount of the corresponding displacement actuator,and sends a command to the displacement actuator.The actuators readjusts the position and posture of the segments to the co-phase state again.Co-phase detection of segmented mirrors.Only when the segmented mirrors are kept strictly in phase,can they obtain the same optical performance as the monolithic mirror with the same aperture.If there is a piston error,the mirror continuity is destroyed,thereby reducing the optical performance of the segmented primary mirror telescope.Since there is 2π ambiguity in co-phase detection,it is necessary to combine the multi-wavelength co-phase detection technology to suppress 2π ambiguity and avoid introducing non-common optical path errors.In view of the fact that large-aperture segmented primary mirror telescope is an important development direction for China’s future telescopes,research on the key technologies of large-aperture segmented primary mirror telescopes,active optical cophase maintenance and co-phase detection technology,has theoretical and practical significance.This thesis specifically completed the following aspects of work:1.By summarizing the development of large telescopes and the implementation form of segmented primary mirrors telescopes by hexagonal segment,fan segment and circular segment,it is clear that the active optical co-phase maintenance and co-phase detection technology of segmented mirrors is the key technology to realize large aperture telescope.2.Based on the topological structure characteristics the segment,an extendable segmented mirrors’ active optical control model is proposed,and the influence of the arrangement of displacement actuators and edge sensor spacing on the active optical control of the segmented primary mirror is analyzed using this model.Aiming at the problems of redundant number of edge sensors in large segmented primary mirror telescopes,large number of conditions of segmented mirrors’ active optical control matrix,unstable control matrix,etc.,the idea based on data fusion is proposed,which uses ridge estimation to improve the stability of segmented mirrors’ active optical control matrix.3.The form of the segment’s support structure of the existing segmented primary telescopes is summarized,and it is pointed out that the segment’s support system uses the Guide Flexure structure to decouple the axial support and the lateral support,and introduces the common problem of the measurement error of the edge sensor.A segment’s kinematics model based on multi-body kinematics theory is proposed,and based on this model,an error correction method based on matrix thought is proposed to avoid Look-up-table.4.The existing co-phase detection technologies at home and abroad is summarized.For the problem of 2π ambiguity in the current co-phase detection technology and the problem that the traditional curvature sensing technology is susceptible to atmospheric disturbances,a combination of multiple wavelengths based on curvature sensing is proposed.An improved particle swarm optimization wavelet support vector machine is used to detect the error range between adjacent segments,avoiding the introduction of non-common optical path errors.5.The noise test experiment was carried out on the edge sensor.A active optical model composed of fan-shaped segments was established,and based on this model,the influence of edge sensor position error and measurement noise on the active optical control of the segmented primary mirror was analyzed.Based on the Matlab platform,the segmented primary mirror active optical integrated simulation system was written.The Matlab-ANSYS interface and the Matlab-Zemax interface based on DDE technology and Zemax macro language were established.The powerful structural simulation analysis capability of ANSYS,Zemax’s powerful optical simulation analysis capability and Matlab’s excellent data processing ability highly integrates the segmented primary mirror active optical technology,which facilitates the establishment of the error analysis and distribution model of the segmented primary mirror system,improves the efficiency of error analysis and distribution in the design stage,reduces engineering technical risks,and is beneficial to Fast iteration of the active optical technology solution to the optimal solution.The simulation system was used to simulate and analyze the influence of the shape and size of the stitching sub-mirror,the piston error and the tip / tilt error on the imaging quality of the optical system in segmented primary mirror telescope.