| With the increase of the diameter of ground-based optical telescope and the wide application of the open dome,the imaging quality of the telescope system decreased by the disturbance of the wind load becomes more and more serious.In order to meet the requirement for space target detection and ensure the quality of the optical imaging system,it is very important to quantitatively analyze the influence of the wind load on the image quality at the design stage and effectively correct it.4m ground-based optical telescope system involves mechanical,hydraulic,control and optics.In this paper,the influence of wind load on the imaging quality of 4m ground-based optical telescope is analyzed by integrated modeling method,and the corresponding corrective measures are put forward.In this paper,the CFD model of the 4m ground-based optical telescope is simulated.The Zernike polynomial is used to fit the wind pressure of the primary mirror.The principal component analysis and harmonic superposition simulation of the fitting coefficient are carried out.Therefore,transient value of mirror pressure is obtained.Secondly,the sensitivity matrix of optical system is derived based on the linearization theory of misaligned optical system.The opto-mechanical system model of the 4m ground-based optical telescope is established by the preprocessor of the opto-mechanical interface.and the opto-mechanical model was reduced by balanced truncation.Then,the dynamic model of 4m primary mirror hydraulic whiffletree support system is established by using the bond graph method.Primary mirror position are calculated.And the control model of primary mirror hydraulic servo system is established.Then,the Guyan reduction technology is used to calculate the response matrix of primary mirror.And the bending mode of active optics is obtainedby singular value decompose.Hydraulic reaction can be as the feedback of active optics to correct the distortion caused by wind loads,and the correction efficiency reached more than 70%.Finally,the integrated model of 4m telescope was established in Simulink,and then the Strehl ratio of the image system is analyzed in different wind speed and different elevation angle.The results show that the Strehl ratio of the image system is greater than 0.8 in the wind speed80%v under any elevation angle,the4 m telescope can work normally;while the Strehl ratio of the image system is less than 0.8 in the wind speed98%v under any elevation angle,the image quality was seriously affected,the 4m telescope is not able to work effectively.The 1.2m mirror hydraulic support test system is built to verify dynamic performance.The index error of dynamic performance through experiment and simulation of integrated model,is less than 15%,so the validity of integrated model of hydraulic support system is validated. |
