Research On The Cryogenic Micro-displacement Actuator Of Segmented Mirror Telescope

Large aperture telescopes will be need with the further development of astronomy, large aperture radio telescopes have higher resolution and sensitivity. Active reflector technology laid the foundation for manufacturing the reflector of large aperture radio telescope, it adopts smaller aperture panels to splice the reflector with a certain surface precision. In order to let the surface precision of reflector meet the imaging requirements of radio telescope, the micro-displacement actuators are needed to support and adjust all the panels. As the supporting and adjusting mechanism of panels, the micro-displacement actuator is a core component of active reflector technology, it’s also a precision linear displacement output device.The Dome A of Antarctica is excellent for astronomical observations, it is generally considered the most attractive site on earth for optical/infrared astronomy, and almost certainly the single best site for submillimeter and terahertz astronomy. Fabricating large radio telescope in Antarctica will promote the progress of the polar astronomy of China significantly and bring about unprecedented challenge to the micro-displacement technology in extreme observation site. So, the research on cryogenic micro-displacement actuator for active reflector technology has important scientific significance and practical value.Firstly, on the basis of access to lots of literature, the cryogenic micro-displacement actuators with two kinds of structural styles were designed, and precision analysis of the actuators was carried out; Next, the influence of low temperature on material performance was analyzed, according to this, the suitable material of actuators was selected, and the finite element model of actuators is established, linear static analysis and mode analysis of actuators were proceeded next.Secondly, temperature field analysis and thermal-mechanical coupled analysis for cryogenic micro-displacement actuators were proceeded. The operating environment in Antarctica was analyzed first, the thermal loads in operating environment were acquired, the temperature curve and temperature field of actuators in operating environment were acquired through simulation analysis; Next, according to the acquired temperature field, thermal-mechanical coupled analysis for actuators were proceeded, acquired the stress and deformation of actuators in operating environment, according to this, the strength of actuators was checked.Finally, performance tests of actuators were proceeded. Output displacement of actuators was detected by length gauge, the performance indexes of actuators at ambient temperature were acquired first, include effective travel, stepping accuracy, repeatability, positional accuracy and linearity, and the stepping accuracy with maximum axial load; then, the cryogenic performance tests of actuators was proceeded, the performance indexes of actuators at low temperature were acquired, and the contrastive analysis to performance indexes at ambient temperature was proceeded in the end.