High Angular Resolution Tilt Mirror For Ground-based Telescope

Raising the telescope's resolution helps astronomers observe more distant stars and clearer celestial structures.The tilt mirror technology has the ability to adjust the beam tilt/tip and piston,so that the ground-based telescope in the near-infrared to achieve co-phase,to overcome the atmospheric turbulence,entrance pupil diameter and other factors on the telescope resolution.The tilt mirror acts as a light beam propagation direction adjuster in the optical path,and its performance has a direct influence on the entire optical path system.The tilt mirror tip/tilt(co-centering)precision is at least 0.03"can the ground-based telescope achieve the co-phase in the near infrared at 1.55 microns wavelength.Traditional tilt mirrors generally pursue a large range of deflection angles and rarely have high angular resolution.In this dissertation,a tilt mirror that satisfies the application requirements of future telescopes is studied based on the high angular resolution for the ground-based telescope.The research contents are as follows:(1)Analyze the requirements of the angular resolution of tilt mirror for ground-based telescope in the near-infrared to achieve co-phase,to guide the design of the tilt mirror.Analyze the relationship between the main performance indicators of the tilt mirror and the components,and design guidance for the key performance indicators of the tilt mirror.(2)Based on the high angular resolution of the tilt mirror,a piezoelectric stack-type tilt mirror scheme was proposed.The high angular resolution of the tilt mirror is achieved by using a dumbbell-shaped flexible hinge and a rhombic attenuated displacement structure.A theoretical and simulation model was established for dumbbell-type flexible hinges and rhombic attenuated displacement structure,and structural parameters were optimized for design.A closed-loop control system of tilt mirror was designed.(3)From the mechanism,the hysteresis characteristics of the piezoelectric stack actuator are analyzed,and a digital PID controller based on the multi-function USB module is designed to improve the positioning accuracy of the piezoelectric stack actuator.(4)To study the characterization method of the performance parameters of the tilt mirror system,a high-resolution tilt mirror test system based on an eddy current displacement sensor was set up.The angular resolution,deflection angle range,response time,first-order resonance frequency and tilt mirror profile were analyzed.Based on the above research content,the creative point in this dissertation is that a piezoelectric stack type high angular resolution tilt mirror is proposed,which achieves high angular resolution and reduces design costs through a simple mechanical design,and tilt mirror prototype is fabricated successfully.Complete relevant performance characterizations.