In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced...In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced by digitally controlled line-tilts of rows and columns. It has not only provided a cost-effective designing methodology in optical physics but also led to a much finer precision of 1 mili arc sec or less. As examples of the application of the proposed digitalised optics, two case studies have been given： a 10 m Schmidt telescope （off-axis） and an 8 m Cassegrain telescope （on-axis）.展开更多
Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic...Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic Gaussian(LQG)control,disturbance feed forward(DFF)control,and disturbance observer control(DOBC)of Tip-Tilt mirror to reject vibrations are first reviewed,and then compared systematically and comprehensively.Some mathematical transformations allow PI,LQG,DFF,and DOBC to be described in a uniform framework of sensitivity function that expresses their advantages and disadvantages.In essence,feed forward control based-inverse model is the main idea of current techniques,which is dependent on accuracies of models in terms of Tip-Tilt mirror and vibrations.DOBC can relax dependences on accuracy model,and therefore this survey concentrates on concise tutorials of this method with clear descriptions of their features in the control area of disturbance rejections.Its applications in various conditions are reviewed with emphasis on the effectiveness.Finally,the open problems,challenges and research prospects of DOBC of Tip-Tilt mirror are discussed.展开更多
文摘In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced by digitally controlled line-tilts of rows and columns. It has not only provided a cost-effective designing methodology in optical physics but also led to a much finer precision of 1 mili arc sec or less. As examples of the application of the proposed digitalised optics, two case studies have been given： a 10 m Schmidt telescope （off-axis） and an 8 m Cassegrain telescope （on-axis）.
文摘Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic Gaussian(LQG)control,disturbance feed forward(DFF)control,and disturbance observer control(DOBC)of Tip-Tilt mirror to reject vibrations are first reviewed,and then compared systematically and comprehensively.Some mathematical transformations allow PI,LQG,DFF,and DOBC to be described in a uniform framework of sensitivity function that expresses their advantages and disadvantages.In essence,feed forward control based-inverse model is the main idea of current techniques,which is dependent on accuracies of models in terms of Tip-Tilt mirror and vibrations.DOBC can relax dependences on accuracy model,and therefore this survey concentrates on concise tutorials of this method with clear descriptions of their features in the control area of disturbance rejections.Its applications in various conditions are reviewed with emphasis on the effectiveness.Finally,the open problems,challenges and research prospects of DOBC of Tip-Tilt mirror are discussed.
