Reflector adjustment for a large radio telescope based on active optics

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The reflector deformation caused by gravity, temperature, humidity, wind loading and so on can reduce the global performance of a large radio telescope. In this paper, considering the characteristics of the primary reflector of a 13.7 m millimeter-wave telescope a novel reflector adjustment method based on active optics has therefore been proposed to control the active surface of the reflector through the communication between the active surface computer and embedded intelligent controller with a large quantity of displacement actuators, in which the active surface computer estimates and controls the real time active surface figure at any elevation angle, reduces or eliminates the adverse effects of the reflector deformation to increase the resolution and sensitivity of the radio telescope due to the more radio signals collected. A Controller Area Network /Ethernet protocol converter is designed for the communication between the active surface control computer as a host computer in Ethernet and the displacement actuator controller in Controller Area Network. The displacement actuator is driven by a stepper motor and controlled by an intelligent controller with the data from the active surface computer. The closed-loop control of the stepper motor improves the control accuracy greatly through the feedback link based on the optical encoder.